Need some help, /fit/. My brother is thinking of joining the national guard because I'm in it but he can't even do a single proper pushup, let alone 40. His running is great, he's on par with me (~12-14 minute 2-mile) ,but he can't do a single pushup and his situps suck. He's not too overweight, he's 5'9 and 190, so I definitely want him to improve on his pushups, what really helps? Should he start doing the girl pushups to get used to build up to it? He's only 16 so he has plenty of time to get himself prepared.

Tl;dr: how to build on pushups if someone can't even do one