No push-ups, just attention.
2016 here, and I agree: pink envelopes are a great way to get noticed. One ambitious and extroverted Squad Leader read a poor New Cadet's letters from his girlfriend aloud to the entire platoon, so writing everyday may not be best.
All said and done, I probably couldn't have gotten through the summer without being able to write home.. I would have lost my mind!
Good luck to you and your New Cadet.