How do you get back to training after an injury without repeating it?

Get a diagnosis first — the plan for a disc issue and a muscle strain are not the same, and guessing wastes months. Then reload gradually rather than resting until it feels perfect, because complete rest weakens the tissue and the pain often returns on the first hard session. The usual principle is finding a version of the movement you can do without provoking symptoms, however small, and building from there. Pain up to a mild level that settles within 24 hours is generally acceptable; pain that lingers into the next day means you moved too fast.