I am so used to conventional wisdom that you have to do 45 minutes of cardio in order to burn calories and get in shape. I have always been a huge runner until I got an injury that has prevented me from running.

So in the meantime I have been doing the mountain climber elliptical 5-6 times a week 45 minutes, but honestly have not noticed ANY change in my body composition.

I know mark talks about steady cardio, but I haven't exercised in two months due to an injury so I thought doing cardio would start to help me get in shape.

Should I be doing weight training/resistance training instead?

i'm 5'6 112 pounds, a little skinny/fat right now. Am not necessarily looking to lose weight, but would like lower fat percentage, more definition in stomach and arms.