

Maybe never. Some other people also wrote it. But I think only this is not the whole truth: For me I am now running for 2.5 years and I never really stopped feeling like im dying, but I improved over time, so now i am really fast while feeling dead. And you will probably also learn to like this feeling of dying because it shows you you have done something.
Also, yeah there is running in Zone2 for everyone, and thats probably something you should try.
I know that sounds a little bit stupid but: In a way going faster makes things easier. I recently improved my 5k record by a couple minutes (sub 22) and when I compare it to me 2 years ago it is in a way easier, because I only need to run at my peak speed for less time. I am sure with time you will have a similair experience.
But in general if the ending is hard and the beginning easy then you should start/run at a slower pace at least a couple times on this distance.