I asked my lil' bro about what he did at the Fire Academy (West Metro - Denver) and he said it was all bodyweight/calisthenics type of stuff. Yes, you have to carry hoses and people, eventually, but just to get in shape for what they will put you through you don't actually have to do those things (if you don't want).
Fitness 666 has a good grasp on what to do and how to do it. Plus it's free. I would suggest looking at that and seeing what you think.
People too weak to follow their own dreams will always try to discourage others.