Newest reason to work out: You'll make more money at work

Other studies have shown the flip side: That people who are not in good shape tend to make less money. A 2007 study, for example, found that women who were obese earned, on average, 18% less than those who weren’t. Those who were overweight also had a family income that was 25% less.

The latest study defined regular exercise as working out at least three hours a week. Considering the average wage in the U.S. is $23.41, the time workers spend at the gym is valued at $70.23 – but the extra pay the exercising employee makes is $84.28, about 20% more than the value of the time spent at the gym.

So even though a lot of people ending up wasting their memberships, maybe your monthly gym pass is worth it after all.