By Peter Hunt
Political correspondent, BBC News
Try telling this to weary, sleep-deprived Liberal Democrat and Conservative negotiators - what they have pulled off is the easy bit.
David Cameron and Nick Clegg face many challenges in the months ahead
It is probably unpalatable after days of frenetic talks, but nevertheless, it is something the two just-joined-at-the-hip parties cannot avoid - there will be plenty of challenges and potential pitfalls in the days, weeks and months ahead.
For now though, for the briefest of moments, both sides will want to savour what they have pulled off.
Not natural bedfellows, they have joined forces - in the national interest, they stress. It is a stable government, they argue.
The lure of getting their hands on the levers of power will, of course, have been a powerful stimulant, to dotting the "i"s and crossing the "t"s.
Out of the hung parliament delivered by the electorate's verdict, the Lib Dems and Tories have conjured up Britain's first coalition government in 70 years.
Lib Dem MPs will sit around the Cabinet table with their fellow Tory government ministers. Individual Tories, expecting high office, will have been sacrificed on the altar of getting a deal done.
To arrive at this position, unthinkable during the worst exchanges of the election campaign, stumbling block after stumbling block has just melted away.
Compromise has been the order of the day.
Just take electoral reform, and wind back a few weeks.
Back then, when David Cameron was dreaming of sweeping an unpopular prime minister out of office on the tide of an overwhelming pro-Tory vote, he was dismissive of tinkering with his party's DNA and abandoning the current first-past-the-post system.
What a difference the brutal judgement of the electorate has made.
As Labour circled the Lib Dems, the Tories upped their offer - they would agree to a referendum on AV, the alternative vote, the most basic form of electoral reform.
Of course, once any referendum is underway, Conservative MPs peers and activists will be free to campaign actively against their new coalition partner's cherished objective.
The talk about electoral reform has dominated the public discussion of the unfolding agreement.
But it is the small print of other details which may yet provoke headaches.
If this new government starts cutting the deficit right away, as the Tories promised all along, how will Lib Dems respond who once feared such action would threaten the fragile recovery?
And how will these getting-to-know each other partners fund the Lib Dem's desire to increase the tax-free allowance on income tax to £10,000?
There will be many more such questions.
Doubts on both sides can probably be quelled, if the individuals are MPs or peers and are close to power.
Across the country, disgruntled activists will be harder to keep on side.
In many places, Tories and Lib Dems have crossed swords regularly and often. They might be reluctant to hang up their weapons.
It was such a groundswell, on the Labour side, which scuppered any Labour Lib-Dem deal.
Its proponents talked publicly of a so called "progressive alliance".
Privately, they hoped the Tories would be sent into the wilderness for decades. It was not to be.
Not least, because the opponents of any cosying up to the Lib Dems took to the airwaves to denounce it, and talked of the need to re-group and refresh the party on the backbenches.
That is where Labour is heading, once Parliament is sitting again.
From this vantage point, they will be watching and waiting for cracks to emerge in the coalition ranged on the government benches in front of them.
The new government will be relieved it has a comfortable majority as it navigates waters this country has not been in since the Second World War.