Hi Lyn!
I can totally relate. These little mind games we play with ourselves to stick through it! 27 minutes to 30 minutes is THREE minutes. A commercial break! Reading a post on 3FC! “California Dreamin’” by the Mamas & the Papas! 3 minutes is nothing but when it's on the end of a workout that already is pushing the limit, it can seem like forever.
I also take it as a sign to change something up. For instance, I was bored with my wednesday morning spin class. So I signed up for a friday class at a higher intensity level. It's a whole new set of exercises that are killing me in a whole different way. Interestingly, it makes my wednesday workout better too because it's my "easy day" now.
The same thing happens when I swim. My comfortable level is the length of swim and not speed. I can swim for hours, days! But swim fast? No way. So I make a deal with myself that I dedicate one part of my workout to sprints BEFORE I do my distance swims. It makes the sprints easier because I know once they are done I can do what I want to do but it also increases the intensity of my distance swim because I am starting out more tired.
Maybe you can try sprinting at a lower intensity at the end of your ride? Something to make you not remember it's the last 3 minutes!