[JamieO]

Well its kinda tough when you rule out running and lifting right away. Those are my two main workouts besides martial arts training, but i think i can give you a few suggestions. For one thing you need to do some sort of cardio EVERY DAY. You are also gonna have to do some type of strength training at least twice a week.

For cardio swimming is a great idea, and the stationary bike is just ok. Personally though i find these things to be a little boring, and if you're doing cardio every day you are gonna want to get some variety. My personal favorite is the heavy bag. Its a great cardio workout and it helps you work on some fighting technique at the same time. It sounds like it would work well for you because it is easy on the knees unless you are kicking as well.

Since your contest is for body fat % loss and not just weight loss strength training is gonna be key. You could easily GAIN weight and lose body fat % if you do enough lifting. For strength training there is not all that much you can do without weights or some sort of resistance training. Just start real light and do sets of 20 or so reps, or do a circuit with real light weights. IMO there is no better lift for overall fitness than the squat, and unfortunately you are gonna have to go real liht on those because of your knee. Bodyweight squats are still good though. Just do sets of 40 or so.

Really you are gonna want to start out concentrating on strength training. This way you can build more muscle at the begining so you will burn more fat througout the process. Just dont make yourself so sore that you cant do your cardio the next day.

Personally i think its easier to get in shape if you set some sort of athletic goal for your self instead of a weight loss/ body fat loss goal. Try to train to make yourself better at a certain sport, get your mile time down, or do a certain length in the pool under a certain time. My goal is to step into the cage in a couple of months, and i dont think there is any better motivation than that.