As for doing 3s for 20 minutes - I can empathize with the feeling, but let me ask you this: how would you feel if you did a set of 3 and then sat down for 5 minutes before doing another set? You only get 3-4 sets like that, but if it takes you that long to be "ready" ... that's what the program asks for. And if you really can only do 2 or 3 sets, then your initial goal over the first 4 week block might be to 1) get used to the exercise/intensity and 2) start adding sets without increasing density. So, in our example, Week 1 Day 1 you do 3 sets of 3, resting 5 minutes in between. Week 2 Day 1 you go for 4 sets with 5 minutes rest, and Week 3 Day 1 you go for 5 sets with 5 minutes rest. You "grow" your work from ~12 minutes to closer to 30 minutes without touching the density of your triples.