Learn to exercise more using "your natural motions......." medicine balls let you easily do this. No two bodies are exactly alike....that's why you shouldn't exercise exclusively on machines. Machines limit you to "that machine's" pre-determined range of motion.
Any personal trainer worth her or his salt will watch to see what your "natural motions" are and adapt the workouts to you!
Medicine ball workouts can be a refreshing way to workout for you and can help you burn more fat.....your muscles will learn to "fire in a more natural pattern."