I think people are lazy to do something because that thing is not interested enough for them to do.
Like me, I am the lazy one to do something that I feel very bored to do like studying in the class that I don't like or have no motivation to study. In the other hand, for the field of what I have been interested in, I am very eager to learn, participate and do something about that.
So, I cannot judge A is lazy or B is studious because I don't know both of them well about their interest. If you are lazy even you do something you love, that means you are surely a lazy person.
Tanawat 4EN 059