Here’s a good exercise. You just hold this pose for a long time. It works your whole freakin body.
Start out lying on your stomach. Then prop yourself up on your toes and forearms, with your arms facing in front of you, and your hands together. Keep your body in a straight line. If your stomach slips toward the floor, you’re too tired or weak.
Hold this for 30 or 60 seconds, or maybe 5 minutes if you’re good. Then do a couple more reps!
P.S. That’s my shirt hanging down to the floor, not my gut!