... following up to myself (why not?), it's also important, I think, to resist the fallacious inference from "X loves his job" to "X would be happy to work all hours". It really does not hold up, but it's distressingly common in conversations like this to hear the proviso "well of course if you love your job you'll work the long hours and that's fine", but one could well love one's job and have other interests one also considers worth pursuing. Nothing to excess! (Plus holding the fallacious inference to be sound contributes to its pernicious contrapositive: "if you don't want to work all hours, you must dislike it here".)

In the book "What I wish I knew when I was 20", the Author brings forth a similar point, stating that doing what you love as a standalone piece of advice isn't that helpful, but a widely held conception. What she advocates is to attempt to find the intersection of "what you love" and "what people are willing to pay you for".

From another point of view, Robert Greene tries to mount the horse from the other side, in his book "The 50th Law", where he brings forth that the mastery of any skill at a sufficient level will make you love that skill (kinda like Intellectual Stockholm Syndrome). So there are arguments from the other side as well.

If we are to follow Greene's train of thought, most work can be made enjoyable through an unhealthy dose of obsession.

On the question whether people are sucessful because they are obsessed, I personally think that it's a contributing factor. The existence of people that are obsessed but not sucessful seems to prove that obsession does not lead directly to sucess, but most people I consider sucessful posess some element of obession.

I actually tend to group people by obsession, for example Tim Feriss, Robert Greene, Neil Strauss, Cal Newport, Stephen Key,Perry Marshal etc. by their obsession for different kinds of Systems.