My theory is that "burnout" is a symptom of the endemic "hero" meme of our culture. Think about all the movies you've seen since the 1980s, the shows you've watched, the books you've read. Embedded in the majority of them is the simple idea that there's something special inside you that can set you apart from everyone else. It whispers seductively to that part of your brain that lies to you about how important you ar…
I hear a lot of people "wanting to play guitar", or "wishing they could play like ". I often ask them whether they want to a) be seen as a great guitarist, or b) actually play guitar. There's a big difference between a and b. A revolves around the idea that you "are" something, and often, where others can see you as being something. B is about actually enjoying to play guitar, for no other reason than playing guitar. No recognition, no fame, no secondary intentions.
Everything you invest large amounts of time in should come from nothing but enjoying that thing you do in itself. But it's not easy. Motivations always get distorted by psychological influences (and that's what you meant by the last line of your comment, if I understood it correctly). There are many people who haven't received much validation or acceptance on a personal level while growing up, for instance. These people will keep reaching, but they'll never reach actual self acceptance. Burnout.
It's really important to confront yourself with issues that you can identify inside yourself, and keep (re)defining yourself. Not what you do, but who you are. What you do should be a consequence of who you are, not a reaction to personal shortcomings you're not looking in the eye directly.
I'm not a psychologist, this is just my take on things.