How the hell is anyone answering with a response beyond "play another game"? I'm a gamer, when I beat a game, hate or love, I play something else when I finish it. There's no worship period for absorbing the awesomness of it, there is only the next game. The longest pause after a game for me is generally real life activities, but that impacts overall gaming time, not just from beating a game.
If you just beat a good game, go get a new game and start enjoying it.