The Portuguese boss publicly criticised Shaw for missing Sunday’s 3-1 victory over Swansea City.
Shaw had told Mourinho on Sunday morning he was not in the right condition to feature against Swansea, but Mourinho insisted he needs to change his attitude.
Speaking about the situation, Neville claims Shaw will need to trust Mourinho if he is to remain at Old Trafford.
“I think Luke is a more complex character,” he said.
“He is young, has moved away from Southampton, and he needs to mature physically and mentally.
“He is such a huge talent but obviously has had injury problems and is not over them from a mental point of view and he needs to work on that.
“He is a young person with big expectation, but he is now in the spotlight at a big club, and Manchester United doesn’t take prisoners.
“Jose Mourinho won’t either because it will be him or the players that are going to survive and he doesn’t work on the theory it will be the players.
“Jose is looking to make his name at Manchester United and he has to make sure he has the players alongside him he wants.”
Shaw has been a vital player since his return from injury and there’s no doubt he’ll feel the pain of his double leg break from time to time.
However, Mourinho wants to build a team of warriors, players that are physically and mentally fit, which is why the Englishman has resulted to training alone at Carrington.
Last season when Louis van Gaal called Shaw fat, he worked on his fitness while his teammates were on holiday and it seriously paid off, hopes are he can deliver the same results once again.