(don't want to put words in GP's mouth, this is my interpretation of it, and my experience)
I do skateboarding and had multiple ankle sprains. What happens every single time is that the wound heals, physiotherapy proceeds and strengthens the whole joint system, and then I'm left with an ankle that is still in pain when it should not physically be anymore since it has fully recovered.
That is, until I literally "decide" the remaining pain is a construct of my mind, and then the pain vanishes overnight, and the ankle that I felt brittle and was scared to use to its full extend suddenly feels as strong and stable as ever, if not more.
In a nutshell, the idea that there's a straightforward causal link between something being physically broken in your body and you feeling pain is simply wrong. Sometimes people feel pain in various body parts without any detectable physical changes and sometimes classical training injuries, like herniated spinal disks, can be found by medical imaging without the person feeling any pain at all. Also the common advice to rest until the pain subsides is often - but no always - wrong; there are plenty of anecdotes of people with completely fucked up knees or ankles or back starting heavy powerlifting program and suddenly healing from their injuries or at least learning to use their body in such a way that the injuries don't bother them anymore.
I dont know about rapidly resuming the activity that caused the injury, but I totally agree that stopping all activity to exclusively rest and recover is terrible. You have to try to walk a bit at the very least.
I participated in a chronic pain study where I personally learned that there are times, much more often than not, that one should not second-guess their joint that is having a flare-up and continue to walk a similar amount each day. I can't overstate how empowering it is to not be in a thought loop on a case by case basis and trust the learned system.
Increased blood flow, released endorphins, usage of muscle, flexing of connective tissues and operation of joints often addresses the issue (if it is not an acute injury that really does need our body's regenerative abilities). We evolved to walk.
Physical activity -- muscle movement -- also increases the flow of interstitial fluid back to the circulatory system. This is how the body "takes out the trash" which is essential to the healing process.
I have a serious medical condition. I sometimes go for a short walk when I feel awful because I know from long experience that doing so frequently makes me feel better and I've gotten good at telling when I feel awful in a way that will likely be helped by taking a walk.
This connects the dots even further! I had a time where I went on a walk and thought it would be an extremely short one. After I thought I had been hitting the wall and I was sure I was making it worse, my joint started feeling much better. I extended the walk and returned feeling like the flare-up I had been experiencing before the walk had rapidly dissipated. That was a defining learning moment for me.
Could you please elaborate on that?