Another contemplative mood

Have you ever thought about the decisions you have made in your life or things that have happened that have led you to where you are now? I know that everything we do and all the experiences we have had over the years, be they good or bad, shape us into who we are, but can you pinpoint something you have done in the past which has had a lasting effect on who you are and the course your life has taken?
I would say the decision that has led me to where I am now (and I really don't know what I would be doing had things been different) was the one I made, when I was still at school, to do some voluntary work one summer with disabled children at a local charity. At the time, did I think I would still be involved 20 years later? Absolutely not. The voluntary work I did that summer, and continued to do on a regular basis, eventually led me to my current job (I manage the charity), which I absolutely love and to a large extent has shaped me into the person I am. Probably more significantly, had I never volunteered there, I would not have some of the wonderful friends I do have, as I met most of my closest friends either directly or indirectly through my voluntary work.
Another turning point in my life was not getting in to Birmingham University (damn that Physics A Level, if only I had a got one grade higher!) and ending up going to Bangor University through the clearing system. Had I not gone to Bangor I would not have the most fantastic best friend who is such an important part of my life- I had already met him shortly before going to university (another one of those people I met indirectly through my voluntary work), but if I had gone to Birmingham, our paths would probably merely have crossed and life would have then taken us in different directions. I have never been so glad to not do well in an exam!
I know that all sounds a little slushy, but I just think it's interesting to look at the events and decisions that have dictated the course of our life. What would you say are your defining moments?