If there is not going to be a goal, then there would not be any discipline. People will chose what they can handle, whether it be in moderation or intensively, to move towards that desired goal. Also, there has be a motivation in order to achieve the desired results in whatever goal to be attained. No matter what method that a student embarks, it has to be a team work, between the student and the teacher, in order to make the student progress towards his or her goals. Most of my students are too young to make concrete decisions about whether or not to pursue piano playing. However, my two oldest students, can make the choices for themselves and reach their desired potential. About the human brain, it can take in as much as we allow it too, providing that we are in good physical and mental stamina. To overdo in anything, would only set us back, and not move forward in the pace or goal, that we would want to attain.
best wishes,
go12_3