Day 13 is the flexibility session, and it earns its place a fortnight in. Three minutes of marching on the spot warm you through, and then nine positions are held for a full minute each, or 30 seconds a side where the position has a side. The sequence works down the body and back up: a kneeling lunge with the hands on the front thigh, then a side lunge to each side with the opposite leg straight and the arm reaching toward the extended foot, a seated forward fold over straight legs, a seated fold with the hands behind the head, a butterfly fold with the soles of the feet together, a kneeling reach with the hips back and the arms long on the floor, a chest lift with straight arms, and a bow pose stretch to finish.

A minute is a long hold, and that length is doing something specific. Short stretches only get as far as the nervous system, which guards the muscle and gives very little back. Around the thirty second mark that guarding starts to let go, so the second half of each minute is where the position starts giving something back. Every position here targets something the last twelve days have been hammering: hip flexors from the crawling and lunging, hamstrings from the jumping, the front of the chest and shoulders from all those push-ups and planks.

In the kneeling lunge, ease the hips forward and down rather than arching the lower back. Side lunges sit the weight back over the bent leg with the straight leg's foot flat. In both seated folds, hinge at the hips with a long spine and let every breath out buy you a little more depth. The butterfly fold draws the heels in and folds forward over them. The kneeling reach pushes the hips back toward the heels while the hands stay forward. The chest lift opens the front of the body with the shoulders down. The bow pose reaches back for the ankles and lifts the chest and thighs together.

Nine positions and a slow clock, and tomorrow arrives easier because of it.

Make it Harder: Not the day for it - stay in each position an extra thirty seconds and breathe your way deeper instead.

Make it Easier: Hold each position for thirty seconds rather than a minute, and rest your hands on your shins in the seated folds.