It depends on how you mean it. You could say Τῆς παρούσης ἡδονῆς ἕνεκα ζῆθι, "Live for the sake of the present pleasure," or Ἐν τῷ παρόντι ζῆθι, "Live in the present," or Καιρίως ζῆθι, "Live opportunely," i.e., at the right time and place. Personally, I prefer the last for its succinctness, but it may not represent your sentiment.