When every day is basically the same (wake, bathe, eat, work, sleep, repeat) the brain basically stops making distinct memories so the last thing you remember clearly is your graduation or that movie you saw last year that you liked. You don't talk to your friends anymore, you drop your hobbies as your job eats up your waking hours and energy. Huge chunks of your life are just copied and pasted. Before you know it, a year or years have passed and all you have to show for it is boredom, malcontent, and the lingering feeling that you missed something. Theoretically, you can quit or take an unexpected trip to somewhere fun, but the truth is, you just don't have it in you. There's work to be done.