Are you driven by a career, a hobby, an activity, a sport? Do you have one or two things that your life pretty much revolves around? Things that people know you by and make up a large portion of your identity (and probably your t-shirt collection)? Would you still be you without that thing? What would do if you woke up one day and it had totally fizzled out on you?
For years it was when I was at work, I loved what I did, I was good at it and it gave me my identity and gave my life meaning. I learned as much as I could about what I did, I studied the classic masters, obsessed about the contemporary leaders in the field and stalked the up and comers and trend setters. I marveled at the people going about it in ways that no one had ever seen and employed crazy science and technology, shredding all preconceived notions of what was right, proper or possible.
Then it happened, the day I got bored, the day I was over it. Nothing had really happened, things weren't particularly different, I just didn't have that thing anymore. I wasn't interested in breathlessly dissecting the minutia of my chosen profession with others who had the same passion. I was still good at what I did. I still cared about doing my best, but my heart just wasn't in it anymore. The worst part was that I felt adrift and rudderless without some kind of driving passion. Was I still me? I had never really had hobbies, my profession was a calling and a hobby and a competitive sport all at the same time. So what was I if I just didn't care about it anymore? Could I keep doing it for the next 20-30 years despite the fact that I was no longer inspired?
I guess I did what everybody does in that situation. I just kinda kept on keeping on, hoping that it would come back (like I watch so many people doing today, in marriages, careers, living situations). I hoped that I would either find my groove again or figure out how to not be bothered by the fact that I was bored out of my mind. That never happened and I was faced with a choice. Live in the low grade misery of boredom or take a risk and do something I liked.
I went with choice B, never looked back, never regretted the decision and began a life I could enjoy again. If you are not happy with what you do for a living, do something else. There world is full of purchasing managers and restaurant managers and mid-level lawyers who love what they do. If that's not you, go find something you love, or are at least willing to do all day. Boredom sucks the life out of a man and there is too much in this world to do to be stuck somewhere you aren't happy.