Did my 20 miler today and it was definitely my worst training run to-date. It was really cold but I started feeling tired around mi 11. Perhaps I wasn't fully recovered from my half marathon last Sunday. Anyway, I was able to make new running friends who kept me going from mi 14 to 17, but once they stopped I totally struggled. Walked the last 2.5 mi, and now been so tired, forcing myself to eat/drink, etc. I'm scared as this is how I felt during my first marathon training cycle back in 2019, and I completely hated running the full marathon. I had been doing well so hopefully this is just a 1-off, but it also shows how helpful it is to run with others. Definitely open to running with someone if they're in the 10:30 mi pace (or a little slower, to be honest).