feet
Thirty years ago or so a chiropractor X-rayed my hips and informed me I had a 6mm leg-length difference, which he said wasn't enough to see with the naked eye but was enough to put my pelvis at an angle and my spine into a slight S-curve, so he prescribed a heel insert. Which I used for a few years, and I think it helped with back pain, but over the years I lost the habit (particularly when wearing sandals), and then forgot which heel it went in. I've looked in a bunch of my old shoes for inserts, and found one pair in which the left shoe has a full-length after-market insole and the right shoe doesn't, so I'm guessing it was the left heel. So on my way home yesterday I stopped at a dollar store (they're really going to suffer from Trump's tariffs, since almost everything on the shelves is made in China!) and got some gel heel pads a few mm thick. I put one in the left heel of each of two pairs of shoes that I wear commonly; we'll see what difference it makes.