1. Not breaking 3 hours in the marathon. I hit my PR of 3:03:54 in 2009 and chased that sub 3 in years before and after that. I think with the right coach and training I could have done it (I didn't have a coach then), but that dream has long passed me by now.
2. I DNF'd in the very hot 2012 Boston Marathon at mile 14.75 after going out at what I thought was a conservative pace, but in hindsight it was not for me on that day. Wish I would have walked/ran to finish, or ever just plain walked to finish. It was not only the DNF in that race, but that one would have been my 8th consecutive Boston, so I broke the chain of going to 10 consecutive Bostons. Have run 9 Bostons since then...2013-2021 (if you count my virtual 2020 run); did not qualify for 2022 (again--missing that 10th consecutive!), but did qualify for 2023.