KANEOHE BAY, Hawaii (AP) -- President Barack Obama is one of the most powerful men in the world. He's commander in chief of one of its mightiest militaries, too.

Yet in spite of all that, Obama feels inadequate from time to time. Especially when he's vacationing in Hawaii and working out alongside strapping Marines at their gym.

Obama visited with troops at the Marine Corps Base near his rental home in Kailua, Hawaii on Christmas. He told them the only problem he has when he works out there is ending up next to some guy who's curling 100 pounds. Obama said "it makes me feel small."

But with New Year's Day approaching, Obama said he's inspired to work harder so he can keep up with the Marines when he returns on vacation next year.