If you don't practice for it, and aren't already working out regularly, it's gonna be hard. If you workout at least somewhat regularly, it'll be easier, but still more difficult because it's not just a workout session. I think my very first time practicing I failed the sledge because I never swing a sledgehammer at a specific target, just wasn't in my skill set. Other guys drop the ladder or can run miles on end but can't crawl through the search tube, etc. Though it IS easier if you're already in shape.
So go sign up for the orientation and the practices. Sign up for multiple practices. They're a lot cheaper than the main test, don't spend the money for the main test until you can pass the practice ones. Make sure you're working out regularly on your own. You don't have to be a Cross Fit fiend by any means, but make sure you run and lift weights and don't neglect one or the other because you need both cardio endurance and physical strength.
Trust me, you don't want to be just barely passing the CPAT (sure you get your card and can apply to FDs) but to actually survive an Academy you want your fitness to be where you can just drop in on a CPAT unannounced and be able to pass.