Any Advice?

I want to start building my self-esteem but I am not sure how I would start. Self-esteem has been a problem for me since around 4th grade and I am in 8th grade now, This whole thing started when someone commented on my weight and that's when I started feeling self conscious about my weight but I didn't really do anything to change it until now, right now I am just changing my diet because I can't really go to the gym, but yeah that's my thing. If you have any advice to how I can build my self esteem than that would be greatly appreciated. ☺️