My knee gave out last month and now I'm rethinking my whole approach to safety

Working in tight spaces for years took a toll on my knees. Last month, during a boiler repair, my right knee locked up and I had to sit out. The doctor said it's from repetitive strain. I've been doing exercises, but I want to know what you all do to protect your joints. Are there specific moves or gear that help? I'm not looking for fancy stuff, just practical advice from folks in the trade.