The signs are already there - the puffy eyes and sometimes flushed face. He rises early, often to go running on the Mall before the traffic gets too bad, and usually works late, either in the Oval Office - at JFK's old desk, which he had reinstalled - or upstairs in the executive apartment.
We know, in part from an intriguing insider-style report in the Wall Street Journal earlier this week, that no day for Mr Clinton is a free day: a recent attempt to take time off to celebrate the birthday of his daughter, Chelsea, was thwarted; when he goes to bed, he is having trouble sleeping.
He does eat. His affection for Big Macs has become a cliche. A group of television news presenters who recently went for lunch with the President tell of how, when a dish was passed round bearing various meats including chops, chicken and steak, they politely selected one. The President chose them all.
If he is able to keep up the pace - and his doctors must worry about the cherry-blossom season in Washington and what it will do to the President's nose and throat allergies - the impression he has apparently given most Americans will endure: that he is working like hell to get things done.
It is this sense of determination that is giving Mr Clinton good opinion-poll ratings, argues Mark Seigel, a Democratic consultant in Washington. 'We have a President who is trying to do something and we haven't really seen that for the past 12 years.'
Much of the President's work schedule is more or less public - the endless meetings with members of Congress to consider his economic plan, the sessions with foreign leaders and the almost weekly campaign trips beyond Washington to sell his deficit-cutting programme to the voters.
More subtly, we are beginning to glimpse a President who, while willing to delegate, rarely is able to let an important decision go by without making some personal contribution. He starts the day by reading the papers - beginning with the Arkansas Democrat Gazette - and transcripts of television news, scribbling comments in the margins for his staff.
Nor is he skimping in his efforts to cultivate the support of all those important to his political fate - especially members of Congress. Take the case of James Jeffords, a not very prominent Republican senator who was sitting in a hotel room in Damascus, Syria, a few weeks ago when the telephone rang. It was the President thanking him for supporting a bill on family leave for workers. The senator was dumbfounded.
He has taken risks. His early efforts to lift the ban on homosexuals in the military undoubtedly backfired. But the public seems in forgiving mood and the received widsom in Washington that any attempt to raise taxes means political disaster may be about to be disproved. Most intriguing, has been the general acceptance - and in some quarters outright approval - of the role given to Hillary Clinton in leading the search for health-care reform.
And, while the press complain that their access to the President is being unreasonably limited, the American people may shortly be seeing him even more than they are already. Plans are being laid for a new television channel that would be dedicated to covering the President's daily activities.
There are even ideas for putting sound bites of the President's most recent speeches on to telephone voice-mail systems in private homes. 'Press 'one' to listen to the President', the message would say on your return home from work. Or, 'Press 'two' if you have had quite enough of the President'.