Warner admits that belief became an issue in Australia's second innings collapse in the fourth Test at Chester-le-Street.
Once the walls started caving in on their run-chase, doubt crept in.
After being swept in four Tests in India, Australia are now 3-0 down in the Ashes after three losses and a draw.
With another five-Test series starting against England in November, Australia are in desperate need of some psychological relief at The Oval next week.
England haven't been much better, but they've grown an extra leg when it's come to the crunch.
Australia are fighting to remember how to win and Warner says that breakthrough victory will bring the confidence back.
"I reckon that's probably what it comes down to. If you have that belief to win, you're going to win," Warner said.
Australia held a team meeting in Newcastle on Tuesday to discuss what they can do to avoid capitulating in the future.
A blistering spell from England fast bowler Stuart Broad was the difference, and coach Darren Lehmann has spoken to the batsmen about recognising those big moments in a match and overcoming them.
"I just know if we got through that last 15 overs we could have easily come back on the final day and won that by lunch," Warner said.
"We spoke about how we could get better. How could we identify those key moments and those key spells like Broad yesterday.
"How could we block out those five overs.
"Put away your shots, you don't need to play any shots until you get a half volley or a full toss."
Warner has long been regarded as an instinctive player but he showed in his second innings 71 at Chester-le-Street that he's become increasingly street smart.
As a left-hander, the 26-year-old is a prime target for Graeme Swann, but Warner played the England spinner with class.
He moved his feet and batted with discipline, refusing to take Swann's bait and hit across the line through mid-wicket.
"I know that he wants me to hit there but I'm not going to hit there at all," he said.
"You can see the line he is going to bowl. I'm batting on the leg stump line and anything that's on that side of my vision I know that he's either trying to get me to sweep or trying to get me across the line.
"But that's up to me to get my feet moving and to try to get that on the full or the half-volley and not get caught in between."