one word , cardio. You need something which will increase the rate of ur heartbeat for a prolonged time period.
Muscles contain limited stores of substances for quick release energy, after these have been exhausted, the body switches to other storage systems, ie Fat. During exercise, for example running/biking, you will feel the difference between ur body using the 2 different methods. Initially it is hard to get going whilst running, first 3-4minutes it's quite taxing, but slowly you level off into a pace which is suitable for you and a pace which you can handle. This is what you should be aiming for.
10-15minute jog every day does wonders, (10mins for an average person is about 2km approx 1.4 miles)