Mashiro;24620 wrote they first look how many you can do and then they train you
Naturally. They are not going to demand that you be able to perform 50 of them as soon as you join up within the allotted time limit. Like you said, they will first tell you to do as many as possible within a time limit and if you cant do too many, you will keep going until you can. If you make their jaws drop with 100 push ups in 2 minutes, lol, congratulations. I dont think they will doubt you at all if thats the case.
