Although his presidency is barely a week old, some of Mr. Obama’s work habits are already becoming clear. He shows up at the Oval Office shortly before 9 in the morning, roughly two hours later than his early-to-bed, early-to-rise predecessor. Mr. Obama likes to have his workout — weights and cardio — first thing in the morning, at 6:45. (Mr. Bush slipped away to exercise midday.)

He reads several papers, eats breakfast with his family and helps pack his daughters, Malia, 10, and Sasha, 7, off to school before making the 30-second commute downstairs — a definite perk for a man trying to balance work and family life. He eats dinner with his family, then often returns to work; aides have seen him in the Oval Office as late as 10 p.m., reading briefing papers for the next day.

“Even as he is sober about these challenges, I have never seen him happier,” Mr. Axelrod said. “The chance to be under the same roof with his kids, essentially to live over the store, to be able to see them whenever he wants, to wake up with them, have breakfast and dinner with them — that has made him a very happy man.”