Is rehabilitation medicine-style exercise the only answer for strength training?

Now that I'm in my late 30s, lifting heavy weights is starting to take a toll.
Even my joints, which I thought would stay fine forever, are starting to feel some pain...
I've tried correcting my posture frequently and seeking advice, but it hasn't had much effect...
For now, I think I need to take a break.
My upper body is still okay, but heavy squats really feel like they are wearing down my joint lifespan...
I follow several orthopedic surgeons, and a significant number of them argue that even standard squats, let alone heavy weights, are bad for the joints.
I've looked at some recommended strength exercises, but they feel more like stretching than actual workouts, so they don't really excite me...
But then again, I suppose that might be what's right for joint health.