Got any links to similar exercises? I'm also early 20s, spend most of my day sitting at a desk, have dealt with backpain for a few years. Pullups (especially wide-grip) have helped but I'd like to know some stretches, too.
I'm in my 30s, but get most of my exercise from cycling, which doesn't exercise the back much. My back pain problems have been increasing over recent years, but I've had good success in the last few months with 15-20 minutes a night of yoga. I'm doing regular plank, bridge, locust, and downward dog poses for back strength, and cat/cow, sphinx, and forward fold poses for back stretches. I like a lot of the leg and hip stretches, too.
Start in a crawling position. The purpose of this is to give you more control of the pelvic position with independence from the chest.
Quote from the PDF:
Start in a crawling position.
Without moving your head and shoulders, roll your hips so that you arch your lower back. Do not push into pain. Only go as far as you feel comfortable with, then relax. Try not to move your upper body & chest. If this is difficult, rest your shoulders, chest and ribs on the couch or bed, keeping your tummy clear. This will help to restrict the movement higher up and help you to localize the movement to the pelvis.
The other thing my physio did was sat with me and showed me what my posture _should_ be like, and made me sit like that for an hour or so. It was then up to me to keep sitting/standing like that outside the office. The first day, I was exhausted after about 2 hours. Now, it's painful to sit slouched.
EDIT: Even though this is a thread about the industry being a scam, I'd still recommend seeing a professional (even just your GP). As other people here have alluded to, you'll probably get some drugs to get you to be able to exercise pain free, but it could also rule out other issues (kidney problems being a good example), and ensure that there's nothing more serious going on.