The following exercises should be done in circuit form. Perform the exercise, one after the other, with 10 seconds of rest in between each. Once you complete the circuit, rest for a minute before beginning the next round.
Beginner: Repeat circuit 2 times
Intermediate: Repeat circuit 3 to 4 times
Advanced: Repeat circuit 5 times
Note: To perform intervals, download an app like Interval Timer and set up the exact number of intervals you'll need (including a set for each leg, if applicable) before beginning. Breathe often, and challenge yourself to see results.
Courtesy of: https://www.active.com/fitness/articles/30-minute-full-body-home-workout/slide-15