I will take it one step at a time.

Physiotherapists don't ask people to go for walks. They ask for the postbox and back. Then the corner. Then the corner and the bench. The knee has no idea it is being managed; it only knows Thursday's distance.

Dread operates at the scale of the whole recovery. Ability operates at the scale of Thursday. That mismatch is why the plan looks impossible from the sofa and merely tiring once you are out of the door.