I definitely have moments like this too. I have been reflecting more lately and trying to decide if the feeling is temporary or permanent. I have been pondering what else I would do. Are you considering a career change, and if so, what would you do instead? I don't know if I could transition to something else without going back to school, and it would kill me a bit inside to take out more student loans.
That's solid advice. I think I have my identity wrapped up too much in my career, so when I dislike my job, I feel unsatisfied in life. I will try to see it as means to an end more than who I am.