Several years ago, I had some problem with my left knee - at unexpected moments, it would emit a stab of pain, and refuse to do what I asked of it - this usually happened when I was using it to step up, for example, on a stile, or on stairs.
My response was to favour it; I'd lead with my right knee going over stiles, and I'd go upstairs one stair at a time.
But the knee has been fine for quite a while now. I don't know exactly how long, because the pain was only occasional, and I'd learned to avoid it anyhow.
Another important thing is, I've lost nearly 50 pounds in weight.
So, in the last few weeks, I've noticed that, impatient with going upstairs one step at a time, I've been going up two at a time, which is how I always (except when carrying something) used to go upstairs.
It's a small thing, but it pleases me immensely.