Teach the young boys how to achieve manhood by example but also sit and talk with them and let them express what's going on with themselves..the anger and pain would release from these young males.
To add to your point, when a boy is being raised by an unmarried woman, goes to schools where the teachers are majority female, he has no clear picture of what "be a man" really means.
To add further to his sense of personal humiliation, his peers are other boys who are dealing from the exact same or similar circumstances.
Speaking somewhat from my own experiences, being a male child is a lot tougher today than it was years ago.
What inspires a boy is being around a man who is willing to do what he thinks is right regardless of all the nonsense that comes from women. And women will give you men a lot of nonsense to deal with everyday. Thats the nature of women, insecurity.
The nature of men is confidence. You can only learn that from another man..... not from being around women all day.
So in part, what does it mean to be a man???
Rudyard Kiplings poem says it in some ways... Its the ability to keep your head, when all others are reacting to what they see..
Stand above the crowd, don't give in to the emotions..... step back, observe, make conclusions, then do what is right... how do you know what is right?.... only time and experience will tell you.