As a young minister you will catch the public eye and enjoy the limousines and some limelight for as long as the government lasts. You will probably rise high in the Cabinet rankings if it lasts another term and you might even become prime minister for a short time as the government heads for defeat.
But you will not be the prime minister you might have been if your timing had been different.
You will not be the completely fresh face a country needs to elect from time to time.
Think John Kennedy, Norman Kirk, Pierre Trudeau, Bob Hawke and Paul Keating, David Lange, Bill Clinton, Tony Blair, Kevin Rudd (they don't always turn out well), Barack Obama, John Key, Justin Trudeau. There is no reason there cannot be female equivalents.
What they all have in common was the fact that when they came to power they had not been in a previous government. That is what made them refreshing for their countries and capable of giving people a renewed sense of national identity and new possibilities. That is the way every aspirant would like to reach the top.
There is a reason all but one of the names above came from the left of their country's politics. The right spends more time in power.
Key had the very good fortune to come into Parliament when his party was languishing in opposition, as Lange did. Bill English was not so lucky. He came in on the National landslide of 1990 and climbed the Cabinet ladder in that nine-year government.
He'd been seen as a future prime minister from the beginning but by the time National turned to him, after its defeat in 1999, he was no longer a fresh face. He was the former finance minister and before that, health minister.
He'd been appearing on TV for years.
This is not a good time to come into the front line of a government if you are a young, ambitious politician with all the attributes to be a great prime minister one day.
He got to lead National to an election against a new Labour government that had taken none of the political risks Labour governments normally took as soon as they got the chance.
No National leader, Key included, could have won the 2003 election. Knowing this, National voters took advantage of MMP to put minor parties into play. Peter Dunne's United Future party did better that year than it would ever do again.
English was dumped post-election not because it was National's worst result on record but because the election had brought Don Brash and Key into Parliament.
Brash came with considerable mana from the Reserve Bank, Key quickly impressed his colleagues with the same leadership qualities that had taken him to the international executive suite. But most important, neither had been a familiar face in a defeated government.
To have been a familiar face in opposition does not carry the same damage. Kirk had been Opposition leader for nine years, losing two elections, before he became a refreshing prime minister.
When I look for the next big star of New Zealand politics I look to the Labour benches.
Not necessarily its front bench. The odds are still against Labour winning next year, especially if English has a youthful new team to announce tomorrow.
Key's decision has no doubt caused many of his ministers to revise their view of how a political career can finish. A number this week have announced plans to retire at the election. English needs to put them out to pasture, and a few more besides.
If he does and National continues to poll high in the new year, we may see Labour's next leader before the election but more likely after it. He or she would be wise to keep their head down a while longer.
If I was in the press gallery I could take a punt. Jacinda Ardern? Stuart Nash? But I haven't seen enough of them. In a way it doesn't really matter. Timing is everything.
Someone will be waiting in the wings, seldom seen or heard, until the tide is turning and their party realises it needs a new face.
Meantime, tomorrow's new ministers can ponder the limits of fate.
