Ican not do push-ups, not even one.

what is the best thing to do?

I'm the same but I started to bench press witch kinda of helped me

It's great your trying to to improve your health first of all, First thing I would recommend is to get healthier foods in your household, ones that hold the nutrients you need to help build muscle, next I recommend to get more active outside with your friends, play games like manhunt, hide and seek, and tag. Next try to do pushups overnight while doing these things. Hope it helped

Iwould say being around others who are not drug free is the wrong step because your peers are likely to influence any new or past habits