As I mentioned before, I’ve always tried to be someone who does push-ups every day. Since June, I’ve done at least 50 push-ups a day (sometimes as many as 100) almost without fail. How? I’ve been using Spar!, which is basically the most addictive and rewarding app I’ve ever downloaded. Right now I’m in a 50-push-up challenge with about two dozen people. Every day, we do 50 push-ups and upload video proof that we’ve done them. If you miss a day, the app charges you $5. At first you do the daily deed just so you don’t lose money. But soon enough, it’s about competing with the people in the group. Then a few days in, another motivation kicks in: The winners (people with the fewest misses) split the pot of everyone else’s fees. So you keep going because you want the reward. I’ve done thousands of push-ups, squats, burpees, and sit-ups (and even did one about cleaning my car and another about writing 500 words a day)—and in the process I also made a couple hundred bucks.