That's got many people wondering: What will she do with them? Take on a new cause? Travel more? Trace the path of another first lady and keep the Obama political brand alive by running for office?
The first lady is a self-described "mom in chief" who also champions healthier eating, is an advocate for military families, a fitness buff and the best-selling author of a book about her White House garden.
For certain, she'll press ahead with her well-publicized efforts to reduce childhood obesity and rally the country around its service members.
"But beyond that, the first lady is exploring ways that she can make a real difference for Americans, not just for these next four years, but for years to come," said Kristina Schake, Mrs. Obama's communications director.
Here are five areas to watch.
When Parade magazine asked last year whether she'd take up any new issues, the first lady identified women's health. "How do we strengthen families and make them healthier, an issue not just in America but around the world?" she said.
Her marquee causes -- the "Let's Move" campaign against childhood obesity and the "Joining Forces" effort to help military families -- took a backseat last fall as she campaigned doggedly for President Barack Obama's re-election.
Look for her to begin publicizing those efforts anew.
Do not expect to see Mrs. Obama push more contentious issues such as gun control or immigration, both second-term priorities for the president. Her public approval rating was 73 percent in a December poll by CNN and she'd like to keep it there.
Still, some feminists remain unhappy that the Ivy League-educated lawyer hasn't used her position to champion what they view as more substantive issues.
Robert Watson, an American studies professor at Lynn University, said he hopes Mrs. Obama will use her popularity to pivot away from the "velvet-glove" issues first ladies typically embrace and say, "I'm swinging for the fence."
Malia and Sasha
The Obama daughters will be in full teenage mode by the summer of 2014. Malia is already there at 14; sister Sasha is 11.
Could having older, more independent children free Mrs. Obama to pursue other interests? Some first lady watchers say that's unlikely.
After all, the teenage years are often full of angst about dating, proms, learning how to drive, going to college and so on.
Malia will graduate from high school during Obama's final year in office, in 2016, and probably trade the White House for a college dorm. She and her parents will have to navigate the college application process and campus tours. Sasha will be in high school.
Presidents and first ladies often step up the pace of international travel in the second term. But it seems unlikely that the president could make such a pivot just yet, with the U.S. public still so concerned about the economy.
One option would be to send Mrs. Obama abroad in his place. The first lady is popular overseas and has been well-received outside the United States, including in India and in Mexico, both in 2010, and in South Africa and Botswana in 2011.
First lady Laura Bush pursued a grueling foreign travel schedule during President George W. Bush's second term. She visited 77 countries in eight years as first lady, including with the president, but 67 of those trips came during the second term, according to Anita McBride, her then-chief of staff who runs American University's first ladies program.
Run for public office
"I have no interest in politics. Never have, never will," the first lady said last year on ABC's "The View." But even those who at one time say "never" can later change their minds.
Hillary Rodham Clinton gave the same answer in 1995 when asked if she'd ever run for public office, says Myra Gutin, who studies first ladies at Rider University. But five years later, there was Clinton campaigning across New York for a Senate seat, which she won.
Clinton used her time in the Senate as a springboard for her 2008 presidential campaign but lost the Democratic nomination to Barack Obama. She became his secretary of state but is departing soon amid speculation that she will run for president in 2016.
Mrs. Obama will be young -- 53 -- when her husband leaves office in 2017. Friends say she has always believed there are ways to serve the country without running for office.
Look for the first lady to continue to be a fashion trendsetter. Everything from her hair to her clothes is scrutinized, with some clothing pieces selling out quickly after she's seen wearing them.
Her new bangs became the talk of this town immediately after she went public with them on her 49th birthday, a few days before the president began his second term.
She also has a new presence on Twitter -- @FLOTUS.