Good exercise routine?!

I am in my teen years and It's not like I'm fat or anything but I don't really do any physical activity. At all. I know this isn't healthy or beneficial in any way so if anyone knows any subtle exercises that I could do and when it would be appropriate to do them so that I can be healthy and in good shape, that would be awesome. Thanks.

P.S. I can't even do one push-up so none of those please :p