You would be the same age or there abouts but the rest of the world would be older since to theoretically achieve time travel one has to travel at the speed of light which of course at present is inconceiveable. According to the Twin Paradox (I think I have to go back to my old physics textbooks to make sure I'll get back on that ASAP) if a twin was to fly to the moon at the speed of light and back while the other remains on Earth, the question has been which twin is older and the answer is the twin on Earth because time remains the same for the twin in the rocket flying to the moon while several years have passed on Earth. This is all in accordance to the Theory of Relativity which even after two years of study on it I still haven't really grasped it. But essentially the time traveller would be younger than the rest of the world.
