Thru's see hiking a bit different when out there than the weekend hiker does. It is your daily job - to get up and hike to the next place. Your goal is to get done, one day at a time, until you reach it. As you get into the best shape ever of your life you realize you can do more and more. Long days become nothing, more that the more miles you do, the less days out there.
You see it in people's journals - the first month they goof off, doing lower miles, spending time in towns. Then the ones that keep going go inside themselves and buckle down.

I watched my good friends do that last summer. By the time they hit Oregon they were ready to be done and were racing for home. 30 mile days were average for them. They didn't sit well, constantly fidgeting, ready to go.

The most I have done in a day is 20 or so miles. I noticed as I hit the bigger miles it became a mental game - I'd count as I hit halfway and once over the hump it was a race in my mind to get to the end.

Did I enjoy it? Yes. It didn't detract from what I was doing.