Leaving a stable job and many friendships and moving to a new city without knowing more than one person. I did this when I moved to London (from Scotland) and

Leaving a stable job and many friendships and moving to a new city without knowing more than one person. I did this when I moved to London (from Scotland) and then to Seattle and then the the Bay area. It was worth it every time but it's scary too, especially when there was no backup plan - if things didn't work out in London, I had no ability to get back to Scotland.