We love body-weight workouts. And why not? A good one can sky-rocket your heart rate, burn a ton of calories, and help relieve stress. The downside: If you have zero equipment—for example, no chinup ...

I once thought my everyday towel was fine. Great, even. It fulfilled its job of getting me dry—what more could I ask for, really? But, as it turns out, I could have been asking for a lot more. That is ...