OK, now this next exercise is good for your upper back.
Lie on your back.
OK, now, you have to bend your knees up, but keep your feet flat on the floor.
Now, bring your knees up towards your chest.
That's right. Now, grab your knees. And very gently pull them as close to your chest as you can - don't force them.
That's easy.
That's not all. Now you have to raise your head and shoulders towards your knees.
Oof.
Do you feel a little tension?
Uh-huh.
OK. Hold it for five more seconds - three ... four ... five.
OK, now don't let go yet. Pull a little further and hold for another 10 seconds.
I can't.
OK, relax. Take a breath.
Now try again.