Day 9 is the same card as Day 1: 20 minutes of running, cycling, elliptical, rowing or swimming at a comfortable pace with the heart rate up, or five 3-minute sets of jumping jacks and high knees in 30-second blocks, with 2 minutes of rest between sets. Second time around, the choice is worth making on purpose rather than by habit.
This is the first repeat of the program's four-day cycle, and repeats are where the program does its work: the same card, met by a body that has now done a week of it. If you took the 20 minutes last time, the intervals are worth a try today, and the other way round - the two options train the heart differently, one long and level, the other in peaks and valleys, and getting both into the month is better than getting only one. If you stick with what you did on Day 1, the aim is to do it slightly better: a little further in the same 20 minutes, or a little crisper in the fifth set.
On jumping jacks, watch the arms as the set goes on; they are the first thing to shrink when fatigue arrives, so keep the hands meeting overhead on every rep. On high knees, the landing should be quiet - a loud foot is a heavy foot. On the steady option, try to finish the second 10 minutes faster than the first, even by a few seconds.
Same card as Day 1, different you doing it - that gap is the only thing the program measures.
Make it Harder: Skip the rest after set 3 and run sets 3 and 4 together as one 6-minute block.
Make it Easier: Take 3 minutes of rest between sets instead of 2 and keep the sets as written.
