Your rest period may involve a complete rest, or, if you have a higher fitness level or are looking to push yourself, it may be an active rest period that includes jogging or performing a boxer’s shuffle on the spot. This fast-paced style of movement will typically take you between 15-45 minutes per session and involves short, intense bursts of exercise, with brief rest periods in between each interval. Designed to push you to your limits, high-intensity interval training is a popular training style for anyone who wants to push themselves and make significant progress towards their fitness goals with quick workouts.