If you run or go for long-distance walks, you can turn your workout into a fundraiser for the charity of your choice. The app CharityMiles tracks how many miles you run or walk in a workout. Corporate sponsors give money to charities based on the number of miles you (and other members) worked out. Over 40 million miles have been logged and more than $2 million has been given to charities like the World Wildlife Fund and Habitat for Humanity. Learn more at charitymiles.org.