One of the first things Michael Bloomberg did when elected mayor of New York was install a new clock at the centre of his team's main office.
It was not a decision motivated by aesthetics or feng shui, but a brutally pragmatic, ever-present reminder of his diminishing window of opportunity.
Every year. Every month. Every second. Like a bomb in a Bond film, it counted down the remaining time Bloomberg had to change New York.
If Barack Obama has a similar timepiece, he could be mistaken for checking its batteries. For a President with three years still left to run, he is already enduring rampant public debate as to who will replace him in the White House come 2016 (this writer, I might add, is as guilty of speculating as any) and what contenders fancy their chances this far out from the election.
Of course, anyone with the arrogance to even suggest themselves as worthy of presidential office must also be concerned with how they will be remembered when their time is done.
And this week, 50 years on from President John F Kennedy's death, the ticking seconds on Obama's second-term clock were falling faster than ever.
At Arlington National Cemetery he joined Bill and Hillary Clinton in visiting JFK's grave: one immensely popular former president by his side, another at his feet.
Clinton and Kennedy are among a select few today with public approval ratings that defy the Republican-Democrat split.
In the same way that Lincoln and Reagan are remembered approvingly by near all and sundry, Clinton and Kennedy boast legacies the Bush presidents do not.
And yet in this same week, President Obama's approval ratings have slid to all-time lows - 39 per cent approval is the same George W Bush scored during this stage of his second term.
The rollout of Obama's healthcare legislation - the key legislative achievement of his first term in office - has proved so astonishingly blunderous that even fellow Democrats are now considering the possibility it may fail.
The problem with political countdown clocks is that as time becomes more sparse it also becomes less valuable. It's like the countdown to a holiday - a year out from the election, half of Washington will mentally check out. Obama's window will already have half shut.
To be remembered for the change he achieved, rather than simply the change his election represented, will take more than a new Obamacare website.