All these numbers are approximates based on an average 145-pound person. However, these numbers provide a helpful guide. Accurate calorie-burning is best measured with a heart rate monitor.

•    Step Aerobics: This targets mainly your legs, hips and glutes; 30 minutes can burn approximately 400 calories.

•    Bicycling: Stationary bikes at home or the gym or cycling outside can burn between approximately 250 to 400 calories an hour depending on the speed and resistance.

•    Swimming: An excellent full body exercise, the breast-stroke can burn up to approximately 400 calories in 30 minutes; other strokes can burn even more.

•    Racquetball: The bursts of sprinting in this sport mean approximately 400 calories can be burned in 30 minutes.

•    Rock-Climbing: While not an easily accessible sport, this activity increases the heart rate and builds arm and leg strength and can burn 380 calories in 30 minutes.

•    Cross-Country Skiing: Although it’s usually a winter and holiday sport, this cardio exercise uses both the upper and lower body and can burn 330 calories in 30 minutes.

•    Running: This is probably one of the simplest and most effective ways to exercise, and you can easily burn 300 calories in 30 minutes and slightly more outdoors than on the treadmill due to added resistance and uneven terrain.

•    Elliptical Trainer: This is another great way to build both upper and lower body strength while increasing your heart rate. You can manipulate the machine to train at a consistent speed to build endurance or to go in fast bursts to increase the cardio impact, producing an approximate calorie burning rate of 300 in 30 minutes.

•    Rowing: Again, outdoors or in the gym, this exercise will increase your heart rate and deliver a great arm workout. Approximately 300 calories can be burned in 30 minutes.

•    Walking: Brisk walking or power walking is a great alternative for those who do not want the muscle stress of high-impact cardio. It is a good calorie burner at approximately 180 for 30 minutes; adding sprinting or hills will deliver faster results.