Dancing cat is a great way to strengthen low back muscles without hyper-extending the spine, which can be uncomfortable for many people. Start on all fours. As you inhale, extend your left leg behind you.
As you exhale, draw the knee toward the nose and the nose toward the knee underneath the body. Round the spine as if finding cat pose to fire up the abdominals.
As you inhale, extend chest bone forward and the left leg back, noticing how your low back muscles contract.
Repeat this three to eight times, then switch sides.