What's really interesting, though, is that you may not even have to technically get stronger to enjoy a boost in self-esteem. According to a 2015 study, overweight and obese adolescents who participated in a four-week resistance-training program improved their self-esteem more than their cardio-only peers, but their improvement in self-esteem was related as much to the feeling of getting stronger as it was to actual improvements in strength.
So yeah, if you want to feel good about yourself, spend some time in the weight room.
You'll stay lean
Yeah, yeah, this is a benefit related to physical appearance, but it's not specifically related to muscle size or strength… except peripherally. You see, muscle mass is thermogenic -- it creates heat, which means it burns calories. When you put on muscle mass, you're basically donning a calorie-burning heat blanket that runs 24 hours a day.