That is true...
And eating healthy helps a lot too.. I kinda scanned through most posts after the first page so i don't know if anyone said that, or it's common sense.
But Doing pull ups could help with your push ups (building upper body strength), and do push ups everyday. It doesn't have to be an overboard amount to where you can't feel your arms, just enough for a work out. Doing sit ups is easy, if your not being timed. So if you've never done them on a regular bases, i'd start with taking it slow the first week or so then speeding it up until you get the results you want?.
And i think it's 1 minute for push ups and sit ups, and a 2 mile run? I know that's the APFT but idk if it applys for ROTC