You really did drink a few beers and barely eat dinner and then ran 21 miles the next morning.
You really did make it through all 21 miles with a right groin/adductor muscle pain that made you worry the previous 4 days whether you would be able to run at all.
You really did run at an easy pace for the first 10 miles, then speeded up so that the last 8 were fast. FAST.
You really did run better and more comfortably in those faster miles, with the groin pain fading significantly as you ran more.
You really did have the thought that if you just added 5.2 more miles, which didn't seem like it would be a problem, you would have PR'd your 26.2 time.
You really did exercise restraint, being smart and stopping at 21.
You really did fuel and hydrate well. Remember what you did.
You really did run strong and run well. Remember what you did.
You really did blow that run out of the water. That really happened.