A HIIT workout session involves you doing intervals of exercise that range from between 10 seconds and eight minutes in duration, with you working at around 80-90% of your maximum heart rate for that period of time. HIIT is a combination of brief, very-high intensity bursts of cardio exercise followed by equal or longer periods of rest. Think 30 seconds to a minute of sprinting, followed by a minute or two of walking or slow jogging. Repeat this cycle for just 10 minutes, and you'll complete a HIIT workout. HIIT training is great for all levels. It will be especially effective for beginners.

Determining the perfect duration of a HIIT workout requires a bit of experimenting. I've found that the sweet spot is somewhere in the 20-30 minute range.

One of the many reasons why HIIT workouts are so popular is because they're extremely effective for weight loss. When trying to lose weight, you want to burn fat and build lean muscle to continue to burn more fat. HIIT forces your body to use energy from fat as opposed to carbs.