If you’re like most active people, you stay within a certain effort when you train.  This can be running, swimming, biking, walking, elliptical…whatever.  That effort becomes extremely comfortable for you and you can maintain it for a large amount of time.  Most would call this your aerobic training zone.  But, the human body is an amazing machine and it will, over time, adapt to those levels.  This adaptation makes the benefits and improvements that you once saw in training or weight loss minimal.   This low-end effort is great for fat burning, but for added benefits, try mixing in some high intensity efforts.  These bursts only need to be 20-30 seconds long.  Try 4-6 of them within a “normal” workout.  This will tax other systems in your body and you will boost your fat burning!  Once or twice a week is all you need to mix things up.  Afterall, variety is the spice of life.