You rarely appreciate painless movement while every joint is cooperating.

Painless movement is the default condition until it is not, and while it lasts it is completely uninteresting. Nobody is grateful for a knee that works. That is understandable, and it is also why maintenance so often begins after a problem rather than before, when it would have cost a fraction as much.

Take one joint that currently gives you no trouble and give it a small amount of care anyway. Range of motion, strength around it, sensible loading. Prevention is dull, which is why it is available.