Didnt you join the Reserves? If so you want to do push-ups. I think the military standard in basic training is 50 something in two minutes. Or rather, that is the bare minimum. I found a website that has a pretty good routine that isnt very hard to follow.
http://www.geocities.com/Colosseum/F...2/100push.html
When doing them keep your back straight, head up, and touch your chest to the ground. If you cant complete the "week 1" workout, dont be afraid to do as much of it as you can and then go to your knees and finish. Just repeat the wk1 workout until you no longer have to go to your knees.