"Running, walking, hiking, swimming, aerobics, kickboxing, cycling, rebounding, starts the fat burning after the 15-20 minute mark. Glycogen burns until then. Shoot for 20-60 min 4-6 x per wk.
If that feels overwhelming to you, start with 5-10 minutes, then work your way up to 15-20, then 20-30, and so on. Before you know it, you'll be exercising longer periods of time. Your body will "wake up" and start to like exercising. At some point, your body may even crave exercising!"
--from my book "Real Health Real Life."