It is often spoken about, but so few of us really possess it.
But without real belief, nothing can be achieved, particularly in the field of high level sport.
After watching the Ipswich Jets for the past five years, it is abundantly clear to me that the quality of true belief permeates each and every member of the playing group.
I don't think I have met two coaches, in Ben and Shane Walker, with more genuine belief in themselves and their players.
There is a quote from J.M Barrie, creator of Peter Pan, which is worth considering: "The moment you doubt whether you can fly, you cease for ever to be able to do it."
The Jets coaches and players believe they can fly, in the context of a rugby league match.
If I had a dollar for every time pundits, and they include former Origin and NRL players, said to me "the Jets are great to watch but their style of footy won't work in big games" then I could retire.
They were referring to the use of short kick-offs for restarts, the Jets penchant to throw the ball around inside their own quarter and innovations such as 'the run backwards move'.
Basically, they were referring to the Jets determination to play rugby league without a straitjacket on.
How wrong the pundits were.
Case in point was the start of the second half of the Intrust Super Cup grand final against the Blackhawks, where the Jets scored inside a minute through captain Keiron Lander after a short kick-off by Marmin Barba.
The belief involved in attempting that in a grand final is impossible to quantify.
Short kick-offs don't just pay dividends on the back of luck.
The practice involved behind the scenes to enable Barba to produce a short kick-off in the highest pressure game of the year is not seen by the casual spectator.
There is also an art to retrieving the ball from such kicks which has been practised diligently.
It is worth considering another quote from J.M Barrie: "Dreams do come true, if only we wish hard enough. You can have anything in life if you will sacrifice everything else for it."
And sacrifice is what the Jets have done.
There is no fitter team in the competition, and that is due to the intense training sessions that are conducted each pre-season which have seen those not prepared to make the required sacrifices ordered to their cars.
The quitters drive away from North Ipswich Reserve never to be seen again.
Shane Walker says "there is no quit in our boys".
To wear a Jets jersey, that never say die quality is a pre-requisite.
It was fascinating to listen to Jets fullback Carlin Anderson tell me how he became more confident under the high ball, after self-doubt plagued some early efforts when he switched to the number one jersey.
A natural talent, Anderson said he would take 50 to 100 bombs at each training session to fine tune his skills.
For a young man born with abilities few possess, he has realised talent will only get you so far and that sacrifices must be made.
Billy McConnachie, who once had limited ball skills to say the least, can now throw spiral passes and pop balls with the best of them.
He has put in the hard yards to take his game to another level.
My favourite quote after the Jets' 32-20 grand final win came from McConnachie.
He won the Duncan Hall Medal as the man of the match after a ferocious display in attack and defence.
I said to him it was a great effort considering he was up against former NRL premiership winning forwards Neville Costigan and Glenn Hall.
He looked me straight in the eyes and said: "Names mean nothing to me."
It spoke to me about the belief that resides within the man they call 'Madness'.
He would have taken the same approach had he been up against star NRL props like Jared Waerea-Hargreaves or Matt Scott.
Going back to that original quote from J.M Barrie… you would have to say the Jets are flying now.
They are certainly flying to Sydney on Saturday, before taking on the Newcastle Knights in the interstate challenge clash on NRL grand final day.
It didn't happen overnight, but I am true believer now myself.
And I am backing them to fly back on Monday with another trophy in the cabinet.
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