Two things you should probably do:
1. Go buy "Get Selected" and follow the training model in the book. Also there's a whole section on this board that talks about PT. The thing you want to do is train smart - be effective but also not trash your body. You'll get plenty of time to do that in the Infantry and (if you make it) SF.
2. If you're bored, get FM7-8 and a Ranger handbook. Know small unit tactics. It will help you in any combat unit.
Good luck. Now do some push ups...
