Not convinced that those dead lifts can lift your mood? Check this out: A growing body of research suggests that exercise can relieve symptoms of depression, including sadness, irritability, stress, fatigue, anger, self-doubt, and hopelessness. It’s unclear exactly why, but researchers think that exercise’s effect on endorphins and other mood-lifting neurotransmitters may be at play. Exercise also lowers your levels of the stress hormone cortisol and helps you to sleep better. Okay, I think that’s enough reasons to work out — now get to the gym and start feeling better!