boys who are not physical become men who are not brave

"When boys play at war they are rehearsing their part in a much bigger drama.  One day, you just might need that boy to defend you." 

[physically and/or emotionally or spiritually]

"Those Union soldiers who charged the stone walls at Bloody Angle; the Allied troops that hit the beaches at Normandy or the sands of Iwo Jima-what would they have done without this deep part of their heart?" 

[the aggressive bit] 

"Life NEEDS a man to be fierce- and fiercly devoted.  The wounds he will takethroughout his life will cause him to lose heart if all he has been trained to be is soft.  This is especially true in the murky waters of relationships, where a man feels least prepared to advance.  As Bly says, 'In every relationship something fierce is needed once in a while.'  Now this longing may have been submerged from years of neglect, and a man may not feel that he is up to the battles he knows awaits him..."