The human mind can make for a cantankerous companion, confounding when it may liberate and liberating when you think it may consternate or even collapse.
Perfect preparation doesn't always lead to perfect performance.
In fact sometimes quite the opposite is true. A scattered or distracted preparation can have you humming and a faultless preparation have you playing a dirge.
Twelve days and three Tests into the international season and the Wallabies have secured the James Bevan trophy against the Welsh – just, but frustratingly missed out on the Hopetoun Cup against the Scots after an abbreviated preparation.
Preparation for Saturday's 25-23 Wallabies victory over the Welsh in Melbourne was certainly far from ideal for Wallaby five-eighth Berrick Barnes, who rushed to and from Sydney for the birth of his first child. However, impressively it didn't deter him submitting a man-of-the-match performance.
While it's uncontroversial to say that most fathers' role in the birth suite is secondary to the mother's, it is nonetheless a maelstrom of an emotional experience, unlike anything you have experienced or can properly prepare for.
The subsequent last-minute flight, the hurried cab to the team hotel and the pulsating 80-minute dash of rugby would have seemed relatively simple for Barnes, if not surreal.
In time Archie will be proud of dad's efforts, but he should spare a bouquet for his mother, who thankfully didn't quite share the 30,000-plus fans at Etihad Stadium at her delivery.
I'm not sure of Barnes's involvement in the suite but, despite a build-up where Test rugby would have been his furthest concern, Barnes delivered on the field.
His goal-kicking was almost flawless, as was the way he took the ball to the line, particularly in setting up Rob Horne for the Wallaby try right on half time. Up until that point the Wallabies had dominated but not led.
The lead then changed nine more times, climaxing after the final siren, saluting the Wallabies and shattering the gallant, skilful and somewhat unlucky Welsh.
It was far from perfect from the Wallabies but a win against quality opposition, in such dramatic circumstances, promises progress towards greater consistency.
Such consistent and reliable performance is largely driven through agitation, either external or internal.
Some athletes and teams create their own agitation. David Pocock is one, the All Blacks another. They seem to replicate high standards week in, week out, independent of the weather, the opposition or the phase of the moon.
The team leader is vital in the drive for consistency and in Pocock these Wallabies have a man to follow. In fact they have an equal in James Horwill when he's fit. And in Will Genia and Stephen Moore or Tatafu Polota-Nau, among others.
In fact they are developing a serious group of leaders throughout the team who are models of consistency in preparation and performance.
And this is important as one good leader might win you a Test but probably won't deliver a trophy of any merit, and he certainly won't deliver you a World Cup on his lonesome. You need five or six leaders through the team to do that.
Even then it won't just happen, but it at least gives you a ticket to play. And it is through these leaders, and the consistency they demand, that the other stars are allowed to shine. Enter Kurtley Beale, James O'Connor and perhaps Quade Cooper. Get this balance right and the Wallabies can not only compete with the best, they can be the best.
Don't get it right and in the competitive world of international rugby you will wallow in mediocrity.
On Saturday night the key reason the Wallabies beat Wales was their ability to turn negative momentum around in an instant. Just as there is a premium on leaders, there is also a premium on players who can stopan opposition in their tracks.
Pocock did it at numerous critical times at the breakdown. Nathan Sharpe and Rob Simmons stymied Welsh progress in the lineouts.
Wycliff Palu did it through some brutal defence. And Digby Ioane does it through his incisive and robust zigging, zagging and general terrorising, most valuably when there is nothing obviously on.
Momentum thieves dishearten the opposition, eating at their confidence, dousing the flames of their ambition, while simultaneously puffing the chests of their own team.
In the end it wasn't so much the fact the Wallabies won through the laser-like boot and steely nerves of Mike Harris at the last that mattered most, but the manner in which the victory was achieved.
When all was not running their way, when they were behind on the scoreboard and, perhaps most crucially, when they would have lost in these circumstances in the past, this time they triumphed.
There is a potentially thrilling road ahead for these Wallabies and it will be better for all their previous travails, both comfortable and compromised.