Tempo runs are not fun

OK, what are tempo runs? Tempo runs are where you run for an indeterminate distance for a set amount of time while doing warm up run, 80% effort run, and cool down run. Now this is why they are not fun for me...I have a hard time with a long warm up and then to run at 80% what does that mean? and a cool down? I don't get it, the training plan tells me to listen to my body and run accordingly. My body likes having a set mileage to go and let me run and run fast. Well, I ran about two miles tonight doing a tempo run and I am not sure if I did it correctly, but I listened to my body. My body and my mind were not 100% into the tempo I can feel myself wearing down a little on the training schedule and that means I need to get mentally tough and re-frame my brain. I remind myself that half of the good feeling that comes from completion is pushing when you have no motivation to push. It has been a long time since I have hit a physical wall and at times those can be the easier ones to over come.