Hart has been backed as the nation's number one goalkeeper by manager Roy Hodgson despite a series of blunders at club and international level over the past year.
Now Shilton, a double European Cup winner with Nottingham Forest and England's most capped player with 125 appearances in goal for his country, wants Hart to shrug off the debate and prove the critics wrong.
"It's only tough if you let it affect you," said Shilton. "He's got to show the true character of a top keeper and I am sure he will do. Forget the criticism, get out there, train hard and look to the next game to prove people wrong.
"Something has happened in the last year. I don't know whether he has lost his focus, but he's not quite the Joe Hart who burst on the England scene. That's obvious. There have been quite a few mistakes but some terrific saves as well.
"He is the best goalkeeper we have at the moment, though his form has dipped. We don't want to be changing the defence around going into important games.
"There are things he could improve upon (in technique), but because of his natural confidence, his agility and his natural reflexes he compensates a bit for that. But room for improvement is a good thing in a young goalkeeper.
"I don't think it's right that I should be giving him a goalkeeping lesson in the press leading up to two World Cup games but he has proven he has got the ability to do well. He's had some good games for England, in Brazil he had a great first half. All I'd say to him is be more determined and work hard in training."
Shilton does not subscribe to the theory that Hart is missing top competition at Manchester City and with England, where Norwich's John Ruddy (one cap) and Celtic's Fraser Forster (no caps) are his current understudies.
"He should be setting his own standards," said Shilton. "He shouldn't have to be pushed by competition. He should be pushing himself. He needs to get back to the form he was in when he came into the England side. We need a really confident Joe Hart."
Shilton knows all about the trials of World Cup qualifiers. He played in the infamous qualifier against Poland at Wembley in 1973 when he spent most of the game watching the heroics of the opposing goalkeeper Jan Tomaszewski as he kept shot after shot out of Poland's net.
Shilton admits making a mistake for Poland's goal in that game, diving too late and allowing a Jan Domarski shot to squeeze under his body.
While England equalised through a penalty from Allan Clarke the 1-1 draw meant England did not qualify for the World Cup finals.
Forty years later the pain of that result remains sharp in Shilton's mind and he is praying history does not repeat itself.
"Looking back it wasn't a dolly mistake but I learned from it," said Shilton, who was speaking at an event with Vauxhall, the England sponsor. "I changed my technique from that moment on and had a coach who taught me body movements. I developed my game in a different manner and became a better goalkeeper from it.
"It's still one of those moments people always bring up and was one of the worst, if not the worst, moment of my career. It was devastating."
It meant Shilton had to wait until 1982 before sampling World Cup action and he believes the incentive of playing at football's top tournament in Brazil next summer should supply the edge for Hodgson's men to qualify.
"You can't have any bigger incentive than wanting to go to Brazil and play in the World Cup. That has to be the biggest incentive for Joe and the England team," Shilton said.
"I'd say grasp it with both hands, make it happen and make sure you don't miss out."
Shilton is confident Hodgson is the right man for the job and believes England will record positive results at Wembley against Montenegro on Friday and Poland the following Tuesday.
"But we have to make it happen, we can't just hope it will happen," he added. "The players have to be really determined and give 110 per cent and make it happen. If we do I'm pretty sure we'll get through."