Maybe you're not living according to your own definition of "success". You may have been motivated over the years to fit in to what you thought you were supposed to be doing, climbing a ladder, mastering the field, making more money, etc. And now you've reached a high wrung on that ladder and you're realizing it doesn't feel like what you thought "success" would feel like. You don't feel fulfilled, you don't feel genuinely interested. Maybe take a look inside and see if there's something else you'd rather be doing with your one wild and precious life.