The PRT standards are a good place to start from, but if you are training for OCS, you're gonna have a bit more than sit-ups, push-ups and the run to worry about. DIs are great at inventing horrible, nearly impossible exercises. As silly as it sounds, if you can do some bare crawls (getting on all fours with your butt in the air) and LOTS of leg lifts (hold your legs out 6 inches as long as you possibly can, lift them up to 90 degrees and rest for a couple seconds then repeat until not able to stand), side-straddle hops (jumping jacks, clapping your hands behind your back) you'd have a small head start. As for push-ups, try lifting your legs about a foot or so off the ground, doing 3 sets of as many as you can. Do 3 sets of regular maxed out push-ups. Then do 3 sets with your arms elevated or against the wall. If you do this a couple times a day for a couple weeks it should really help. And make sure you practice some diamond push-ups too.