The First Lady encourages the nation to work out as part of her Let's Move! initiative, a fitness and nutrition campaign aimed at fighting childhood obesity. "The overall message of Let's Move is balance," she says. "Do we have a vegetable on the plate? Have we incorporated fruit? What's the portion size? Portion sizes have gotten out of control."
After his historic victory in 2008, President Barack Obama wins re-election, beating Republican nominee Mitt Romney for a second term in the White House. "I wouldn't be the man I am today without the woman who agreed to marry me 20 years ago. Let me say this publicly: Michelle, I have never loved you more," Obama says during his victory speech.
Four years after selecting relative unknown Jason Wu to design her gown for the inaugural ball, the first lady picks another look from the hot designer for President Obama's second celebration, a custom ruby red chiffon number with velvet halter-neck, leaving Wu himself "in shock." The evening gown caps off a stylish day for Obama, who dons a Thom Browne coat, jeweled belt, Cathy Waterman earrings and Reed Krakoff boots for the swearing in ceremony at the Capitol.
Four years after bringing home Bo, the Obama family adds Sunny to their brood, a 1-year-old female Portuguese water dog. "Sunny is the perfect little sister for Bo – full of energy and very affectionate," reads a statement on whitehouse.gov. "The First Family picked her name because it fit her cheerful personality."
A day after turning 50, Obama marks the milestone birthday with a crowd of 500 in the East Room of the White House, dancing the night away. "It was just an incredible party, chock-full of celebrities," a guest tells PEOPLE of the affair, which was attended by Beyoncé, Paul McCartney, Jennifer Hudson and more. "You could tell she had a lot of fun."
BIOGRAPHY (top to bottom): Kevin Lamarque/Landov; Scott Olson/Getty; Chip Somodevilla/Getty; Pete Souza/White House; AP