Interviewed by Matt Lauer on NBC's "Today," Obama said the women around the president "want him to be healthy, and he's worked hard at it, and I'm very proud that he's been able to kick the habit."
Asked how he achieved nearly a year smoke-free, the first lady said, "I don't know. Once he made the commitment to quit, I left him alone, because it's a very personal thing. ... When a person is doing the right thing, you leave them alone."
Obama said they have "done a good job" giving Sasha and Malia as normal a childhood as possible, but the Secret Service's protective bubble has its advantages, like keeping the girls off Facebook.
"I'm not a big fan of young kids having Facebook," she said.
The first lady also vowed the president does not dye his hair.
"No, he's pretty gray," she said. "I think if he had known he would be president he would have started dyeing his hair like 10 years ago. ... Now it's too late."