More P.A.C.E. exercise, thanks to Dr. Al Sears:

Remember to do these two things:

Use progressivity – Little by little, you increase the intensity of your exertion over time
Apply acceleration – Try to reach your intensity target faster, and reduce your recovery time.

1.  Stand with your feet shoulder width apart

2.  Bend slightly at the knees and lean forward, arms hanging straight down

3.  Squat down, and as you come back up, swing both arms up and back in a windmill, as if you were doing the backstroke in a pool using both arms at the same time

4.  Return to start position and repeat until you are slightly out of breath

5.  Recover

6.  Do three sets, with recovery periods in between
In the P.A.C.E. studio, we use a 5-7-9 progression for intensity. That means do the first set at what you perceive to be a 5 on your intensity scale. Do the second set at 7, and the third set go almost all out, leaving a little room to where you could have done a bit more.

Every time you work out, you’ll be a little more fit. Your perceived exertion will change over time so that your “5” of today will only be a “4” tomorrow. So you have to progressively increase your intensity to match your fitness.

That might mean adding a little jump to your squat. Or doing two backstrokes on the way up. Or adding a few more squats to each set but trying to do them in the same amount of time. It’s P.A.C.E. as long as there’s a tiny increase in intensity with each workout.

Then, you accelerate the intensity. Instead of resting for three minutes between sets, only rest for two. Then one minute. Then 20 seconds. Also, instead of a 5-7-9 intensity progression. Try for 6-7-9. Then 7-8-9. Eventually you’ll be able to go 9-9-9 right from the start.
Acceleration is so beneficial because it gives you energy fast, that you can feel right away.