In Swedish there is a term called självdistans, which would be directly translated to "self-distance", which means possessing a certain objectivity towards yourself, to be ego-less or not taking yourself too seriously. In other words, it's a quality in a person that would be modest and not too egoistic. Important thing to stress here is that an apparent lack of "self-distance" is a negative thing while too much self-distance can also be seen as a negative trait as it would been that you are actively trying to avoid giving yourself credit for something you have done, or dismiss any praise you might get from others.
I am not sure if what I am trying to get at is clear enough or if I should try to explain it better. At any rate, I am trying to find a word or expression to express the same quality but I can't seem to find "self-distance" in any English dictionary. Is there a good, semi-formal word that fits in this context?