If this isn't motivation to start hitting the gym in 2013, we're not sure what is.

52-year-old Sean Penn showed off his absurdly ripped body while hitting the beach yesterday in Maui. He might want to invest in a shave and a haircut, but if nothing else, just scroll down on the photo so you can't see his head.

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It looks like we'll also be seeing Sean in some other things this year besides swim trunks. His next film, Gangster Squad, hits theaters next Friday. In addition, he plans to continue his Good Samaritan work in helping to rebuild Haiti, which has still been devastated by the January 2010 earthquake there.

What do you think of Sean's beach bod?

Photos courtesy of Getty Images