the hardest 8 minute arm exercise with trainer to the stars tracy anderson!
My favorite run lately! Torch almost 400 calories in 32 minutes: Run at speed 7 for one minute, walk on 15 incline speed 4 for 3 minutes. Repeat 8 times. Also will keep your body burning fat long after you've finished working out. Intervals are actually better than running for a straight period of time!
Another cardio workout you can do at home! -- this page has a whole bunch of these workout