Definitely, it's not just about the act of exercising, but also the exposure to other people, situations, environments etc. that helps. If you just exercise in a basement by yourself you won't experience the same antidepressant effect as participating in a fun social activity.

This. It’s a shared suffering kinda thing that results in tighter friendships too. There’s a reason Crossfit is so cult like, save this is a huge part I’d argue. Not only that, but especially in high school when what others think of you or how you perceive others view you - being fit and capable at something, gives you confidence. I personally owe a lot of my current love of fitness, confidence, and social skills to having played sports in high school. Lately I’ve struggled with depression, but any time I fall off the wagon and get back on, it only takes a few weeks before the feeling of confidence and positive self image start coming back, which bleeds into my confidence and mental well being everywhere else.

Good on you for paying attention to your kids friends and making sure they aren't socially isolated!