My own conclusion about burnout is that it fundamentally comes down to who controls the agenda, and how much you invest in that agenda. I've been burned out. Many years ago, early in my career. My cure: I was in the lucky position that it was a good time to spend a year and half going back to school to knock off a graduate degree that simultaneously moved my career forward, gave me a total change of scenery, and gave me some break time between leaving the job and starting classes, time that I devoted 100% to hobbies and home improvement projects. And of course, an easy-to-tell story when reentering the job market.

So on the topic of agenda... if what you are working on is your own agenda, you don't burn out. You might change the agenda by redefining goals, but in the end, you are sailing your own ship. Not only do you not burn out, it is curative. It is when you absorb someone else's agenda and make it your own to an unhealthy extent that you burn out. Always be computing that dot product between your employer's agenda vector and your own agenda vector. Don't over-invest beyond that dot-product.