Tell him to be assertive - positive - bloody-minded and downright determined. the New scientist published the findings of a report that had the statistics - in as far as these things can be quantified - the finding was: those people who were the most positive and extrovert before achieved the swiftest results and the furthest recovery. When doing the physio it helps to shout at the leg or any limb if only in your mind. The reasoning is that it overloads the nerves (or synapses or whatever) and makes new pathways for the signals. The sooner the result the better the muscles condition (muscles are not damaged they atrophy). AND do it soonest. You have to encourage him.
Take Mick Tems' case. He assured me he he had tried it and was convinced it was achieving progress. Seeing him walk at Miskin festival when he had been in a wheelchair but two months previous is testimony.
Enough - convert that shock into action - now - tell him to SHOUT AT IT