Typical nerdy guy here.
If you can do a few push-ups you should be fine. Flaring your parachute feels like it's around 20 lbs of resistance. Your front riser maneuvers will feel like doing a chin-up as well so some basic athletic ability is needed. You'll be fine for learning how to skydive, but you should hit the gym anyway, working out is awesome. Good luck dude! Let us know how your AFF goes!