True virtue is unisex. Traits often associated with masculinity such as self-confidence, resilience, and responsibility are also useful to women.
Aye, I think that is the tragedy here. Boys are taught that masculinity is, in itself, a merit, beyond its actual functionality. If we were to decide upon beneficial traits based on criteria such as happiness and life success impartially we would find ourselves drawing from both masculine and feminine arenas. Whereas we've come to the point women and girls are now, to a greater degree, allowed to draw from the masculine well, the same can not for the most part be said to be true of boys drawing from the feminine well. That is still very much taboo.
So we have praise put on ways of being that deny both success and the self. I'll list a few initial thoughts to maybe get things started.
Do not be afraid or uncertain.
Uncertainly is necessary for education and learning. We must recognize a position of uncertainty, of ignorance or inability, to agree that we need to learn as thus act on such agreement. Fear is inevitable and denial of fear will only make us behave in irrational ways, most likely directing our fear into irrational anger. "Courage is being scared to death... and saddling up anyway." John Wayne - A better example of how a man or a woman should relate to fear.
Do not feel or express emotion.
More than anything this has an effect on life satisfaction and happiness. One needs to be able to be capable of feeling and sentiment to enjoy life's pleasures. Perhaps a lack of feeling and expression of such can aid in career success but...to what end? What is the point of having wealth or status if you can't enjoy it? Of course, society doesn't care if this is the case. It is more beneficial for society that they have their worker bees.
Always be in control
Either in control of oneself or others. Obviously, this is a good way to sabotage team work. It also turns any potentially nurturing relationships into dominance struggles. One in which not the strongest or most capable prevail, but the most ruthless and dishonest.