I like where this post was going, but I don't thing it got there. Energy is a factor, but what about the value of one's effectiveness? It's not merely time, or energy that gets things done, it's effectiveness.

If I have all the energy in the world and all the time I want, it does not follow that I'll get more done. If I'm into what I do and I'm good at it (talent + interest) I'll be more effective and that's of much greater value than how much time and energy I put in on a given day.