... some thoughts from Nassim Nicholas Taleb. (Hat tip, Dave Lull.)
Good, of course, should be done for its own sake. We should eschew thoughts of heaven. One life at a time.
On the other hand, C. S. Lewis points out that "If you read history you will find that the Christians who did most for the present world were precisely those who thought most of the next. It is since Christians have largely ceased to think of the other world that they have become so ineffective in this."
More here (courtesy Dave Lull).