I used to go to the gym regularly. I definitely remember how hard it was to do pull ups and dips when completely untrained. I had to start with negatives. It seemed impossible at first. Now I haven't been to the gym for almost a year but still occasionally do some bodyweight exercises. I can still knock out 10 pull ups, 40 press ups, dips etc. all from a dead stop. It's amazing really. I have less muscle than a lot of people now, but I seem so much stronger still.