Nope, that is just a matter of personal preference. Once you have ran enough you reach a level where you can just slow down a bit and running will be easy. I li

Nope, that is just a matter of personal preference. Once you have ran enough you reach a level where you can just slow down a bit and running will be easy. I like the hard runs but I also like the easy relaxed runs. I recently did a casual very long run, 70 km, and the group of us ran at a relaxed pace, talked shit, stopped to eat several times and just chilled. I only started to get tired at around 62 km. It is like a hike but a bit faster (9 km/h while running) and running motion instead of walking. Obviously if you do not want to plateau in your training you have to run hard some of the time, but not every run has to be hard.