Got a treadmill? Torch fat and boost your metabolism with this workout from Shreadmill creator Felix Montano:

5 min: Walk at 4.0 speed, 4.0% incline
2 min: Increase speed to 6.0-6.5
(Rest: 90 sec at 2.0 and 1% incline)
90 sec: 6.0 speed at 3% incine.
90 sec: Sprint your fastest at 3% incline
(Rest)
90 sec: 6.0, 5% incline
(Rest)
2 min: Raise incline to 12% and walk (no handrails!)
(Rest)
90 sec- 2 min: Sprint your fastest at 0% incline
2 min: Walk at 2.0 speed and 0% incline

With interval training you really get your heart rate up without torturing yourself. Video Here: