File this under Wow! Not only will this customized-for-you workout bring you a sleek physique, it can actually help you be forever young: When researchers studied the lifestyle habits and DNA of 2,400 twins, they found that regular exercisers had longer telomeres, tags at the ends of our chromosomes that shorten with age, than their couch potato counterparts did. In fact, as few as 30 minutes of activity daily resulted in telomeres that looked 10 years younger. Slimmer on the outside, younger on the inside…we'd say that's a happy result all over!