Rolling Like a Ball
Sit on your mat with your knees up and your hands on your shins. Check that there is room on your mat behind you. Do not do this exercise if you are having problems with your neck.
Roll backwards until you are on your upper back. Then rock-and-roll forward until you are balanced on your sit bones. Continue to roll back and forth, balancing at both ends of the roll.
This should feel good, like a back massage. If it does not, stop.