I started off running 5k, and that was hard. I pushed that to 10k, and it didn't get any easier.
Then I started doing a half on Sunday, and that was difficult as well.
However, they all seemed to take up roughly the same mental time, if that makes sense? I didn't start thinking, halfway through - WTF LOL, although I will admit that the half always gets tough at the 18k stage.
As has been said, I think your baseline for what is normal pushes out with the distance you do.
I started off running 5k, and that was hard. I pushed that to 10k, and it didn't get any easier.
Then I started doing a half on Sunday, and that was difficult as well.
However, they all seemed to take up roughly the same mental time, if that makes sense? I didn't start thinking, halfway through - WTF LOL, although I will admit that the half always gets tough at the 18k stage.
As has been said, I think your baseline for what is normal pushes out with the distance you do.