I actually got into the habit a while back of making sure I stand up and stretch after every block sewn. When I'm drinking coffee or tea when I'm quilting, I don't fill up the cup completely, so it forces me to get up out of my chair more to get another fill-up. While I'm up, I take long, hard stretches, fingers to toes, bend over deep and hang my hands down to relax my spine and put it back in place and then when I sit down again, I always take a second to make sure my posture is correct, roll my shoulders back and start sewing again.
I've got a sciatica problem that likes to light up the left side of my back from my neck to my toes if I sit too long and then get up to move, so I do what I can to make sure I don't upset that nerve. I just don't like making that nerve mad and believe me, there are times where it's just downright angry at me and I've had moments where it takes my breath away, so I'm super careful.