The stereotype of "manly" is a self-contradiction. The are stereotyped accepting whatever abuse that comes from a hazing ritual to become a member of a group, but they're also supposed to be independent and "not take crap from nobody." Deer hunting is considered a "manly" activity, but it involves someone attacking like a coward rather than according to honor: giving the opponent equal footing by removing the element of surprise and making both sides fight bare-handed (never mind the honor issues of fighting an opponent that does not consent to battle). They are supposed to be slick salesmen and leaders with integrity. Reckless thrill-seeking can get themselves and others hurt or killed. Getting tossed into the prison system serves to make them ineffectual and unable to "provide" for themselves, much less anyone else. At some point, we have to acknowledge that "manly" lacks a clear real meaning that a person can live up to -- never mind whether "manliness" is a good thing in the first place.
It's a rubbish term. Instead of telling people to "be men" (which is astonishingly told to boys, who lack the age requirement to be "men" anyway, as illustrated in the first post), we should tell them to "be good people." Tell people exactly what they're supposed to hear. They don't need a stereotype -- they need good values. If the "right" thing to do is to perform some stereotypically-manly objective, you can offer lines like "tough it out," "stick with it," "deal with it," "fall down 7 times, get up 8." Amazingly, they'll work with women and children, too. People respond more positively and persistently with directions than insults (especially when those messages are internalized), so there's no reason to ever settle for something sloppy and ineffectual like "man up."