With HIIT, you will be working harder than you normally work but for about a quarter to a half of the time that you would normally spend on the cardio machine of your choice. HIIT is so intense and effective that you only need 15 to 20 minutes, tops!
Here's What You Do:
Pick the cardio machine of your choice (treadmill, elliptical, rower, bike, swimming) and perform a 5 minute warm-up. Then take time to stretch properly and you are ready to begin. Start at a moderate pace for 1 minute, then crank up the pace to 90 or 95% of your Maximum Heart Rate (MHR). Continue at this effort for 15 to 20 seconds, then slow down to your starting pace for another minute followed by another all-out sprint for 15 to 20 seconds. Or do like me and jump as high as you can, as fast as you can for 30 sec and rest for 30 sec. Do this for no more than 15 minutes. After that, finish your workout by cooling down for 5 minutes and thoroughly stretch afterwards.