Life is funny. As a businessman, public speaker and author, I especially love clever stories with a message because they make important points more memorable.

Over the years I have collected a filing cabinet full of great material. Since April is National Humor Month, I thought I would package up some of my favorites, which cover a variety of topics. Enjoy!

Unless you are a one-person shop, teamwork is not optional. This story says it all:

A minivan pulled into the only remaining campsite. Four youngsters leaped from the vehicle and began feverishly unloading gear and setting up a tent. Two kids then rushed off with their dad to gather firewood, and two others helped their mother set up the camp stove and cooking utensils. A nearby camper marveled to the father, "That is some impressive display of teamwork."

"Actually," the father replied, "I have a system. No one goes to the bathroom until camp is set up."

It's all a matter of perspective. When you wake up every day, you have two choices. You can either be positive or negative; an optimist or a pessimist.

It's like the two salesmen who fell on hard times and ended up broke in a small town in Montana. They needed money to move on and learned that the town paid $20 each for wolf pelts. They sensed an opportunity. That night, they set out with a couple of clubs and some borrowed supplies and made camp in the distant hills. They were no sooner asleep than one was startled by an eerie howl. He crawled outside the tent to find himself surrounded by hundreds of snarling wolves. Back into the tent he crawled and shook his buddy.

"Wake up!" he cried. "Wake up! We're rich!"

Believe in yourself, even when no one else does. At the end of a particularly frustrating practice one day, a football coach dismissed his players by yelling, "Now all you idiots, go take a shower!" All but one player headed toward the locker room. The coach glared at him and asked why he was still there.

"You told all the idiots to go, sir," the player replied, "and there sure seems to be a lot of them. But I am not an idiot."

Confident? You bet. And smart enough to coach that team someday.

Take care of the customers you have, and they’ll take care of you. A man who had lived an exemplary life died and was given a preview of heaven and hell. In heaven, people were peaceful, serene and smiling. In hell, he was given a stretch limo, the best of food and drink and an endless list of parties. He chose hell.

As soon as he walked through the gates, the devil began flogging him with a whip and he was thrown into a fiery chasm. “Wait!” he said. “Yesterday I was treated like a king, and now this. Why?”

“Ah,” said the devil. “Yesterday, you were a prospect. Today, you’re a customer.”

If you’re not in it to win it, you’ve already lost. Determination is what keeps us hammering away. It’s like the young high school sophomore who was doing his best to land a job for the summer.

“Look here,” said the office manager, “aren't you the same young man who was in here a week ago?”

“Yes, sir,” said the applicant.

“I thought so. And didn't I tell you then that I wanted an older person?”

“Yes, sir,” said the young man. “That's why I'm back. I'm older now.”

Every survival kit should include a sense of humor. Albert Einstein’s driver used to sit at the back of the hall during each of his lectures. After a period of time, the driver said to the famous scientist, “Boss, I’ve heard you give that speech so many times ... I could give it in my sleep.”

So, at the next lecture, Einstein and the driver switched places, with Einstein sitting in the back, dressed in the driver's uniform. The driver gave the lecture flawlessly. At the end of the lecture, a member of the audience asked a detailed scientific question. Without missing a beat, the “lecturer” replied, “Well, the answer to that question is so simple, I’m going to let my chauffeur who is sitting in the back answer it.”

Mackay’s Moral: You can take your work seriously, but be careful not to take yourself too seriously.

Life is not a parabolic curve, nor does it go straight up. There are a lot of lumps, a lot of bumps. I have never yet met a successful person who hasn’t had to overcome either a little or a lot of adversity in his or her life. Overnight success is much more of a myth than reality.

Remember the four-minute mile? Humans had been trying to do it for centuries, since the days of the ancient Greeks. Historians found old records detailing how the Greeks tried to accomplish this. They had wild animals chase the runners, hoping that would make them run faster, among other measures. Nothing worked.

So, the experts decided it was physiologically impossible for a human being to run a mile in four minutes. Our bone structure is all wrong. Our wind resistance is too great. Humans have inadequate lung power. There were a million reasons -- until one day a human being proved the doctors, the trainers and the athletes all wrong.

In 1954, Roger Bannister showed the world that it could be done. Over the next few years, more and more people broke the four-minute mile once they realized that yes, it was possible.

When Bannister passed away this month, it brought back a lot of memories from that time in history that I remember so well.

The world was changing a great deal. People around the world were overcoming the long-perceived physical boundaries of nature. American pilot Chuck Yeager broke the sound barrier in 1947. And who can forget Sir Edmund Hillary and his Sherpa guide, Tenzing Norgay, conquering Mount Everest in 1953?

Many famous people have overcome tremendous adversity to triumph:

-- Bill Gates, co-founder of Microsoft and one of the richest people in the world, dropped out of school and had his first business fail.

-- Oprah Winfrey overcame terrible poverty growing up in rural Mississippi to become a billionaire media mogul who has inspired millions around the world.

-- According to some sources, Albert Einstein didn’t speak until he was 4 years old, and couldn’t get a job in physics for two years after graduation.

-- Richard Branson didn’t let his dyslexia stop him from founding Virgin Group and controlling more than 400 companies.

-- Popular recording star Jay-Z came from a rough Brooklyn neighborhood, but couldn’t get signed to any record labels as a rapper. In 2013, Time magazine ranked him as one of the most influential people in the world.

-- Vincent van Gogh is considered one of the greatest painters of all time, yet he only sold one painting during his lifetime.

-- Simon Cowell, star judge from “American Idol” and “The X Factor,” had a record company fail.

Botanists say trees need the powerful March winds to flex their trunks and main branches, so that the sap is drawn up to nourish the budding leaves. Perhaps people need to meet the stresses of life in the same way, though we dislike enduring them. A stormy period in our lives can be a prelude to a new spring of life and health, success and happiness. That is, if we keep our self-confidence and faith in the future.

Everyone faces adversity, pain, loss and suffering in life. When you go through those periods, it’s hard to remember that the emotions you’re feeling are only temporary. The best thing to do is to develop a plan for what you will do when these times hit and find your way to the silver lining -- the place where you can feel hopeful again.

You need a personal sense of commitment, the ability to let go when appropriate and strong values. Take charge of the things you can control, such as your treatment of others, the way you spend your time outside of work, how you think about yourself, how often you exercise, when and how to share your feelings, how to let others know you’re stressed and how mature you act.

Who says that you can’t accomplish your goals? Who says that you’re not tougher, better, smarter, harder-working and more able than your competition? It doesn’t matter if they say you can’t do it. The only thing that matters is if you say it. So, we all know, if we believe in ourselves, there’s hardly anything that we can’t accomplish.

Mackay’s Moral: How you handle adversity says a lot about how you will handle success.

The popular movie “Darkest Hour” has brought a lot of attention to former British Prime Minister Winston Churchill. It’s also brought a lot of attention to Gary Oldman, who won the Best Actor Oscar for his portrayal of Churchill.

According to biographers, Churchill did not have the happiest of childhoods. Neglected by his uninterested parents, he was sent to boarding school at a young age where he would write letter after letter pleading for his parents to visit him. Most of his requests went unanswered, and he ended up spending a succession of holidays alone at school without even the company of classmates.

Churchill would go on to suffer many failures both at school and in his political life, failures that would have defeated most people. But Churchill kept persevering, overcoming great odds and eventually leading his country through its most difficult times.

How did a man with such a difficult upbringing and spotty professional record achieve such greatness?

The answer may lie in the following story: Churchill was asked to deliver a speech at Harrow, the boarding school he attended as a boy. “Never give up! Never give up!! Never, never, never-never-never-never!” he roared.

What a tremendous lesson in perseverance!

Perseverance separates the winners from the losers. Those who persevere understand that luck is something only failures believe in. Perseverance has other names -- persistence, determination, a can-do attitude. Success in life depends on your willingness to never give up, even when the reward is delayed.

One of my guilty pleasures is that I occasionally stop at McDonald’s for a hamburger and a caramel sundae. The phenomenal success of the Golden Arches franchise is evident throughout the world. How was such a dynasty built? Why is Ronald McDonald a household name? The answer rests in the motto adopted by its founder, Ray Kroc. It simply reads, “Press On.”

As U.S. President Calvin Coolidge said: “Nothing in the world can take the place of persistence. Talent will not; nothing is more common than unsuccessful people with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent.”

In my line of work -- sales -- persistence takes on a special meaning. Somewhere between throwing in the towel and being a pest, you might find wisdom in this Code of Persistence for salespeople, developed by Herman Sherman. Resolve to:

Never give up so long as you know you are right.

Believe all things will work out if you hang on until the end.

Remain courageous and confident when the odds turn against you.

Never permit anyone to intimidate you or shake your belief in yourself.

Fight to overcome any physical handicaps and setbacks.

Try again and again, and yet again, to reach your dreams.

Take new faith and resolve from the knowledge that many successful men and women have had to fight defeat and adversity to achieve their greatness.

A few generations ago, Susan B. Anthony was both a revered and despised political figure. In the late 1800s, she tirelessly fought for a woman’s right to vote, a law that was not enacted until several years after her death. American women have been able to vote only since 1920.

At that time, the majority opinion was that women need not vote or be equal to men, and that anyone trying to change the status quo was simply a troublemaker. Still, Anthony soldiered on, and eventually earned a tremendous following. At a reception given in honor of her work, she was inundated with bouquets of flowers. Recalling her early years in politics, she commented, “They threw things at me then -- and they were not roses.”

Shortly before her death, she was asked if she was happy about how her life had played out. She said yes, she would do it all over again. “The spirit is willing yet; I feel the same desire to do the work, but the flesh is weak. It’s too bad that our bodies wear out while our interests are just as strong as ever.”

Susan B. Anthony serves as an inspiration that one person can accomplish greatness through perseverance.

Mackay’s Moral: Triumph is just the “ump” beyond “try.”