Finn and Rey see some pilots doing the push-ups with their friends on their backs, and they’re like “THIS IS THE BEST THING I HAVE EVER SEEN,” so they immediately try it themselves, but it always devolves into Finn trying to make himself as heavy and inconvenient as possible on Rey’s back while shouting stuff like “no come on I believe in you!!! don’t let anyone tell you your weak arms can’t do this!!” as Rey lies face down on the ground helplessly giggling
If they ever get far enough along to switch roles, Rey’s a merciless and cruel tickler. It’s entirely possible they have never completed one single push up.