Stretching/exercise/physio/massage: yes!
But if you’re someone who works mainly at a desk (at home or in an office), investing in a really good office chair is absolutely worth it for your back. The great ones are wildly expensive new, but can often be found refurbished or second-hand for a fraction of the cost. It might still seem like a lot to spend on a chair but your wellbeing and comfort should be prioritized! I’ve got a Steelcase Leap v2 – highly rec’d.