Try this if you’re stiff, achy, or just want to let your spine re-find it’s natural shape.
Sit on an upright chair (office chair or dining chair is fine. Come towards the front of the chair so your feet are flat on the floor.
Put a hand on the middle of your chest. Look at your hand, allowing your head to get heavy and roll forward. Allow your heavy head to take your whole upper body slowly over your lap, letting go of the hand on your chest, so you end up with your upper body flopping over your lap, arms loose and dangling, head flopped forward and looking at or between your legs. Just imagine you’re a rag doll, and there’s no effort or tension in the upper body – all of it just flops.
Breathe out (you can sigh if you want) and then just let the in-breath come in without trying to ‘take’ the breath. Breathe like this a few times. Enjoy the feeling of tension leaving the upper body. When you’re ready, come up slowly, almost one vertebra at a time, gently curling up to sitting. Let yourself adjust to being upright, and notice how easy and yet upright your posture feels now.