Tim Twietmeyer, who has completed the Western States Endurance Run 25 times, on each occasion in under 24 hours (the world's oldest and most prestigious 100-mile race) is quoted as declaring: "There is nothing noble in being superior to some other man. The true nobility is being superior to your previous self."
Psychologists agree the toughest challenge that elite athletes face, comes not from their opponents, but from themselves.
Andy Murray won the first set of the 2013 Australian Open, but then went on to lose the final to Novak Djokovic. The match demonstrates that at this level of the game, it is mental toughness which determines the victor, not superior technical skill. Djokovic had to control being rattled by his first set loss, while Murray allowed a first set advantage to be whittled away.
At 2-2 in the second set tie break, a feather floated down, distracting Murray from his second serve ball toss, producing a double fault at a critical moment. He is quoted afterwards in the Daily Telegraph newspaper as saying: "I mean, I could have served... It just caught my eye before I served. I thought it was a good idea to move it. Maybe it wasn't because I obviously double-faulted."
The press still don't get that this is all about psychology; the Daily Telegraph does not to see the key implication - that this apparently innocuous event reveals the state of Murray's mind and focus, and instead chooses to report one response to this event is that Ivan Lendl, Murray's trainer, couldn't have anticipated that the mating patterns of the local bird life, should have been in the pre-match briefing.
Mind games dominated the match, indeed, the tournament; a controversial 'tactical' time out by Victoria Azarenka turned her semi-final around against Sloane Stephens at a pivotal moment. Even though the incident was widely reported all around the world, team Murray didn't appear to have learned the crucial psychological lesson.
Instead of going off court for a medical time out (perhaps with more genuine medical need than Azarenka did against Stephens) to keep Djokovic guessing, and perhaps break up his rhythm, Murray chose to have his blister treated, parading it to the whole world, while on court, in the middle of the match.
Djokovic didn't sit down during this changeover, but instead used the cover of 'stretching', seizing the opportunity for a surreptitious stare at the state of Murray's feet. This was a tactical psychological disaster, and the game could only slip from the Scot's grasp once the Serbian understood the true physical state of his opponent.
If the rules of the game allowed Murray to take a medical time out off court, then this should have been his play at this moment. If he didn't choose this option, (if it was available to him) then this reveals an issue for Team Murray in a branch of psychology known as 'theory of mind', which is crucial to the kind of one-on-one competition elite tennis is.
Andre Agassi has described singles as the loneliest sport because, even boxers have the intimacy of their opponent for company in the ring, while on court, the net means no one ever gets close to you.
In the mental jousting that tennis becomes, Murray knew that Djokovic knew about the injury. 'Theory of mind' refers to thinking what your opponent is thinking, about what you are thinking.
The victors deploy mental strategy all the time, but it may be in their interests to keep from the public, press and rivals, just how vital this element in their armoury is to victory. Even so, before the match, Djokovic's coach confirmed in a TV interview that the contest with Murray was going to be primarily 'mental'. That he did so with a broad grin, suggests confidence that team Djokovic felt they had got inside Murray's head.
However, in Britain, there also remains a deep suspicion of brain and behaviour sciences, especially as applied to sport. Perhaps psychology is seen as somewhat 'feminine' in the macho culture of elite competition, or the 'stiff upper lip' 'pull your socks up' brigade may feel behavioural science still just means crying about your childhood to a nodding therapist.
Some sports psychology peddlers who do not base their interventions on data are definitely 'snake-oil' salesmen. But the longer UK Sport turns its back on the vital contributions proper scientific psychology has to make, the more sports fans here will have to endure coming second.
The importance of mental toughness in elite performance, not just in tennis, but all sport and in life is increasingly recognised. But what exactly is 'mental toughness' and how do you get it?
Anna-Marie Jaeschke and Professor Michael Sachs from Temple University in the USA quote in the magazine 'Marathon and Beyond', runner Twietmeyer as one inspiration for a study recently conducted by Jaeschke for her university thesis, advised on by Sachs, of 408 ultra-marathoners. All the participants in Jaeschke's study had run at least one race of 50 miles or longer.
Ultra-marathon running is a sport where by its very nature, the search for mental toughness is most likely to be successful.
The runners in this research rated the top three characteristics of mental toughness as (1) The ability to use failure to drive themselves to further success, (2) When training becomes physically and mentally tough due to obstacles, they keep going by reminding themselves of their goals and aspirations and why they are putting themselves through this and (3) The ability to recognize and rationalize failure while picking out the learning points to take forward.
Mental toughness means coping better than opponents with mental demands of sport; being more consistent and better in determination, focus, confidence, and control under pressure. Jaeschke and Sachs write in their article entitled '100,000 Miles Closer to a Definition of Mental Toughness: The farther you run, the more the mind dominates', that this research suggests mental toughness is the ability to transcend physical pain as well as environmental adversity.
But a key confusion is to mistake stoicism and toughness - stoicism is the Victorian inhibition of emotions, particularly any sign of vulnerability or weakness. Victoria Azarenka when she won championship point at the Australian Open, sobbed dramatically - anyone who has seen Novak Djokovic pound his racket into submission on the court floor, would not see him as 'unemotional'. The dramatic displays of release of emotion after victory, or defeat, in these champions indicate just how much there is pent up on the inside, and the astonishing level of control being exerted.
The key distinction is that the mentally tough can self-regulate: controlling impulses and emotions. They have superior self-confidence, appraisal of achievements, self-esteem, having a sense of purpose and contribution, self-efficacy, belief in abilities and strengths, and also self-control belief in control of one's life: captain of your ship and master of your fate.
Of course, it's easy for sedentary academics to pontificate about mental toughness - it is athletes like Andy Murray who courageously battle the reality of brutal competition.
All the more reason to pay attention to research like that of Jaeschke, as she indicates in her article with Michael Sachs in 'Marathon and Beyond' that she's in training to run an ultra-marathon herself.
Follow Dr Raj Persaud on Twitter: www.twitter.com/@DrRajPersaud