You started off the year completely gung-ho about that new diet and exercise routine. Now that we've officially reached mid-January, we can bet you've probably fallen off the wagon. While pressing snooze on cold winter mornings seems infinitely better than hauling your butt to Equinox, you're missing more than just an ab workout when you skip the gym. We mean, a toned bod is a bonus, but the benefits of exercise extend far beyond the physical. The next time you want to sleep in, read this.

[Photo via @thebaristudio]