Just days after being released from the hospital after suffering from a virus, President Jimmy Carter is back to work.Habitat for Humanity honored Carter and his wife, Rosalynn, at a gala dinner Monday night at the Andrew W. Mellon Auditorium for their years of service with the nonprofit. Carter appeared in good spirits, greeting guests at a reception and making jokes during his acceptance speech. He turned 86 on Friday.Carter noted that his favorite cartoon, which was published in the New Yorker, features a little boy telling his father that he hopes to be an ex-president when he grows up.I think sometimes President Obama thinks about that cartoon as well as I, and everyone whos served in the White House, the 39th president joked.Carter also appeared at a Habitat for Humanity job site Monday. He was discharged from a Cleveland hospital Thursday after recovering from a gastric viral infection. He fell ill on a flight and was hospitalized Sept. 28.