The Jailhouse method works as follows:
Pick a starting point, let's say 20, and do that many lunges.
Everytime you complete a set the next one is decreased by 1. So you do 20, 19, 18... and so on until you finish.
Starting from 20 is called a Jailhouse 20 and by enduring it you will complete 210 lunges.
You can mark your progress on the equivalent set.
Let's get it on!