Sport, as everyone who competes at any level knows, is not just a physical exercise, it's mental. It is the most difficult mental exercise I've attempted, much harder than studying, pondering and writing.
In sport you discover the mind is the one muscle you can't easily control. Often it's your real opponent. I'm in awe of minds that can sink a vital putt, serve out a set, concentrate for 100 runs or play the heart out for 80 minutes of rugby.
I missed the first 20 minutes of the World Cup semi-final. When I came in the All Blacks were down 7-0 and my wife said, "This is not looking good." No worries, I thought, we often start slowly.
But within a minute of watching it was obvious something was wrong. They weren't being allowed to play. As the game went on and nothing was working for them, it got worse. You could see rising numb panic in the eyes of captain Kieran Read. He could feel the World Cup slipping from his grasp and didn't know what more he could do.
They were not up against the England of old - slow, niggly, overweight men in tight vests. England's players now were athletes and runaway bullocks with names such as Itoje, Tuilagi and Vunipola, and they were coached by a wily Australian who knew us too well.
In the week before the semi-final, Eddie Jones said, "The busiest bloke in Tokyo this week will be Gilbert Enoka, their mental skills coach. They have to deal with all this pressure of winning the World Cup three times and it's potentially the last game for their greatest coach and their greatest captain and they will be thinking about those things.
"Those thoughts go through your head. It's always harder to defend a World Cup and they will be thinking about that."
Conversely, there was no pressure on England, he reckoned, "because nobody thinks we can win."
Gilbert Enoka has been with the All Blacks for a long time. He was a PE teacher in Christchurch with a developing interest in sports psychology when he started working with Canterbury rugby teams. These days he is on the motivational speaking circuit as well as the All Black coaching staff and doesn't give much away in interviews.
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But he has said, "I'm intrigued by the 'red-head, blue-head' thinking, where one has you in panic mode and the other one has you convinced you have the tools at your disposal if you stick to your plan."
And he has explained that to pull themselves from a red head state back to blue head thinking he encouraged players to give themselves an action to clear their mind. Brad Thorn would throw water over himself, Richie McCaw would stamp his feet. Kieran Read would stare at the farthest point in the stadium.
I hope Enoka was the busiest bloke in Tokyo last week. His job would have been harder after the All Blacks dispatched Ireland in fine style. Ireland had posed just as much threat as England before that game. Both used the "rushed defence", exploiting that deadly flaw in rugby's rules that makes it easier to advance without the ball.
After the Ireland game nobody was talking about the rushed defence. The All Blacks had worked out several plays to stop it, including the use of pods of three players, usually a loose and tight forward backing the ball carrier, to attack the line with quick turnovers until it was shredded.
They could be forgiven for thinking all they had to do against England was go out and do the same. But Jones had plans to unsettle them. He started with the haka, I think.
Enveloping the haka with a big V was brilliant. The All Blacks were visibly disconcerted. You could see their eyes flicking to the side, unable to stare down their opponents as usual. Rather than presenting a fearsome challenge, the haka resembled desperate warriors facing an ambush.
And for the English the V has a national resonance, recalling Churchill. All these things probably count psychologically.
More important though, England had no intention of playing as Ireland did. They wanted the ball, if only to stop the All Blacks playing with it. And they went about winning lineouts and turnovers, playing with power and pace we did not think they could sustain.
I fervently hope they play the same way in the final tomorrow. This has been a magnificent World Cup for rugby. Millions of Japanese would have seen the game for the first time as they got caught up in the excitement created by the way their team played, the New Zealand way.
Those people probably think rugby is always played like that. If we keep Steve Hansen's legacy alive, it will be.
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