How do you get physically fit within one month?

I am moving to a new place, and since I didn't do too well here in the friend department, I've decided to become a much more likable person. I have already decided that I should be much nicer to other people than I was here, be more socially interactive, and to have friendlier attitudes around people. But that leaves one thing-- physical appearance. I am not too concerned with this one and won't completely change myself for other people because I know as long as I am a nice person, others will like me (save a few exceptions, no one can be friends with all the world). However, I do want to slim down a bit, as of the moment I'm a bit chubby. I have one month until school starts. I have already decided to either run for twenty minutes, or swim for an hour or so every day. I will also try to get off the computer for a while and skip rope or do some jumping jacks and do crunches. And of course I will eat healthy (but I can't go on a complete diet because I am a little short for my age, and I'm trying to eat protein to get taller) But is there anything else I can do? I am seriously determined to get "skinny." Is there any way I can do so by adding or altering what I already have planned?