Why has not playing sports effected my mood?

Ok so i've played football since the 4th grade. Im going to be a 10th grader next year. I quit playing football halfway through the year last year because the coach picked favorites and half of the team were self centered know it alls. Anyway I've noticed that I find myself being really hard on myself lately, I think its because im not playing sports but im not sure. I want to box or play lacrosse, Im leaning more towards lacrosse even though I've never played it before please tell me why sports effect my mood as big as it does. Thank you;)