It’s not working long hours. It’s working on the wrong things — whether for long hour or, over time, normal hours. Here’s what Marcus Buckingham writes in Go Put Your Strengths to Work:
Burnout doesn’t happen when you are working long hours on invigorating activities. Long hours may tire you out, but they rarely burn you out. But fill your weeks with the wrong kinds of activities, activities that weaken you, and even regular activities will start to burn.
This means that burnout doesn’t even necessarily mean that you are in the wrong job. You can be in the right job, doing the wrong things.
So, what’s the solution? Work within your strengths, and cut out the activities that call upon your weaknesses — that is, the activities that weaken you:
Pick a week; capture, clarify, and confirm which activities strengthen and which weaken; then start the week-by-week process of pushing your time toward the former and away from the latter.