Worried about ROTC physical training? HECK YEA! What you think?

Now I am sorry for the detail but I'm worried about ROTC's Physical Training. I played bball and softball in high school but I'm a big girl and endurance is not my thing. So i fear that I will not do well with running and push ups? Can anyone tell me what they think, how bad they thought and how it was, and whether i should worry? I really want to get my physical shape under hold and be fit and have strength and endurance but I am realizing even though this is a great way to do so... the journey will be long and hard... any comments are appreciated