clipped from www.fitfaq.com

Smart Exercise: "Smart" exercise is exercise that provides the maximum amount of benefit in the least amount of time. It's short, sweet, and usually fairly intense but it'll burn a ton of fat and tone up your body quickly.

Perform 30-40 minutes of moderate-intensity cardiovascular exercise OR 7-20 minutes of high-intensity cardio 2 or 3 times per week.

Good cardio exercises include running, bike riding, stair-climbing, elliptical running, and anything else that allows you to keep your heart rate up for an extended period of time.

Perform a light 10-minute warm up (i.e. jog or bike) to loosen up your muscles and joints before lifting weights.

Frequently "mix up" your strength workouts to keep your body from adapting. Change the exercises you perform, as well as the set/rep schemes, time between sets, and the intensity of your sets.

If you prefer - or can only do - low-intensity cardio (like walking) you must do more: at least 40-60 minutes 4 times per week.