Don't try to build muscle it will only slow you down. I went into BCT with all of my high schools weight lifting records under my belt and all the muscle mass that went with it just made running so much harder. 3 years later and I'm still trying to slim down all that muscle. General exercises I would recommend are just push ups, sit ups, running, biking, and swimming. I also recommend finding interesting ways to do said workouts because they get really boring really fast.
I would suggest crossfit,it is geared towards general fitness beyond just whats required for the PT test.Remember your not wanting to get in shape just for the army's silly pt test.Your ultimately getting prepared for future deployments like Afghanistan where guys with scores 270 and up still get broke off by the altitude and climbing.And chief personally when I was still infantry it always turned out the guys your size and strength seemed to be the ones that out performed the scrawny track stars when it came to practicality in the field and on deployments.
i'm looking for exercises to do to prepare for 13B Cannon Crew Member, not basic training. i'm really skinny, but want to be a 13B, and i know they lift heavy stuff, so i just want to now if you would recommend any exrecises to build the muscles up that i would be using as a 13B.
Well it's good to know that being built like a bear can but put to some good use, thanks for the info there Gonzo. Anyway, Fbody, since you are going to be lifting heavy objects it's paramount that you have a strong back. Doing planks and the superman is a good way to start. You can incorporate medicine balls or other LIGHT objects into your workout but just be careful. A look on Mr.Google will bring up some good videos with plenty of examples and explanations.
I would say if you can lift 100 lbs up from the floor and stick it on a feed tray just at belly button level, and do it multiple times really fast for about 5 minutes, your crew chief will love you.