If you've been doing your cardio on the same machine for a while, switch it up. Choose a machine that might be a little more difficult for you. Keep your mind and your muscles challenged so they're always responding to new stimuli. When your body responds, that means it's changing!
Bill Phillip's Back To Fit: Day 58
Hit this cardio workout with energy and intensity! Think of all the good you're doing for your heart, your lungs, and your body composition.