We know from all the books of Musar from the Rishonim, and especially from the Guide for the Perplexed about the importance of good character traits. So no one is doubting that. Rather their question was, "How effective is learning lots of Musar every day in terms of correcting bad character traits?"
I am pretty sure they were not the only ones to question this. Almost anyone who has had any experience with any modern day mashgiach [spiritual adviser] always walks away wondering, "If that is the result of Musar, then what good is it?'' (I can at least say that I have asked myself this question many times.)
For the last few days, I have been wondering about a kind of combination between learning Musar and outdoor skills and survival skills. We already know the entire purpose of the creation of the Boy Scouts was to teach young men good character. And to a large degree it was effective (in the distant past).
I suggest to combine both approaches, Reb Israel Salanter and the Boy Scouts. [My parents encouraged me and my younger brother to go to the Boy Scouts, but we never got very far. I was anyway in those days dealing with school work and other kinds of extra curricular activities and studies. And I had to walk home after school which was a long hike every day. I simply did not have the energy for everything. And I have heard that nowadays teachers assign a lot more homework that they did in my days.
In any case, for health my feeling is there is nothing quite as good as fresh air, sunshine and lots of hiking. And basic thing about camping and survival skills and learning to work with other as team is important for character building--not just learning about good character from books.