It seems you are calling not knowing what to do with yourself a "mid-life crisis". It would be a crisis regardless of your age. Hell, I'm 57, and I still don't know what I want to be when I grow up. I expect to change occupations within the next twelve months--maybe move to a different place or continent. Will I miss what I have to leave behind? Maybe. In the grand scheme of things, however, we all walk our own path in this life. Don't be tied to 'things'. They are just things.