I can't think of just one. There was adopting a son, which changed my life from having responsibilities for no one but myself to making sensible decisions rather than just what seemed interesting in the moment. Then I worked and identified as a paperworker for 15 years, thinking that was what I would do for a living for the rest of my life. Then, there was the switch to EMS, which focused the next twenty years of my life. Then there is marriage, a move to Maine, semi-retirement, and a near-loss of interest in doing things with other people. If I had to pick one, however, it would be adopting a son. Being a single parent at 20 was a big change, and one that affected the rest of my life.