There's a saying that presidents age twice as fast while in office. With Thursday marking President Barack Obama's 55th birthday, take a look back over the past 60 years of U.S. presidents and judge for yourself how much the office aged them.
Former President Carter is seen here talking during a news conference in Atlanta on Aug. 20, 2015. Carter, who was 90 when this photo was taken, was announcing he had melanoma that had spread to his liver and brain. He was treated via surgery, radiation and a relatively new form of immunotherapy, and announced on Dec. 6, 2015, that he was cancer free.