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.