If you’re not used to sleeping on your left side, it can take a little bit of effort to get comfortable with it. Try sleeping with a pillow between your knees or at your back to discourage rolling. Another trick, if your partner agrees, is to move to the other side of the bed. This forces your brain to decide again which position is “right” and you can more easily make a new habit of sleeping on your left side.
However you accomplish it, left-sided sleeping clearly has many benefits and may just be the key to the kind of rejuvenating sleep you’ve been missing.