As an art student at the academy, without a doubt my favorite class was live model drawing.
It's hard to explain the kick one gets when a drawing becomes more than just a couple of lines on paper. It has something to do with a level of concentration and focus which gracefully allows you to forget anything that was previously on your mind. It also has to do with a sort of epiphany you experience once you fully understand the underlying anatomy of the subject you're trying to capture.
It will suddenly, effortlessly, all make sense. There is no more trying, the pursuit is no longer that of "making a good drawing", in fact there is no longer any sort of pursuit, other than to delve further into this elusive level of reality you have been fortunate enough to hit upon.
There are other realms where I have encountered this kind of almost zen-like focus, where labourous effort at a certain point makes way for effortless understanding. One is to play music, the other one I shall not elaborate upon -- though you are free to guess!