Failed healing
Most of the time it’s hard not to heal. You couldn’t stop it if you tried — not that you’d want to. The body is going to recover from most kinds of injuries almost no matter what — it’s just a matter of time. As long as you were reasonably healthy before you were injured (and you don’t smoke or otherwise abuse your vitality), healing will usually progress inexorably.
Chronic pain is different by definition: it doesn’t stop when it’s supposed to. Either healing itself fails, or the pain continues even when the tissues are fine, or a bit of both. Overuse injuries or repetitive strain injuries (RSIs) like carpal tunnel syndrome and plantar fasciitis are slow-motion traumas that often seem immune to recovery — this is what makes them both terrible and fascinating. They are not as simple as they seem.