Thanks for the replies. It's interesting that both of you mention that it's not my job to fix him and he has to take care of his own issues. That's exactly how I feel, but part of me feels guilty for feeling that way, as though I should be trying to do something.
He has no interest in helping himself other than a couple half-hearted "I should stop drinking and hop on a treadmill" sort of statements, but that never happens.