This is a really great question, and pretty astute observation!
The line / distinction I can see is this:
When I can start defining myself by my own values and my own sensibilities, I am becoming the man I want to be.
When I allow the actions of others to define who I am (or who I think I am), then I am prone to taking on masks of masculinity that aren't mine.
I have direct experience with abuse, bullying, and the mask I took on. Hyper masculine (read: angry), very thick walls, stoic, emotionless. That was a result of the bullying I received, and I had created this thick masculine personna because there was no way in hell anyone was ever going to find out about my "disgusting" sexual urges. As long as I acted hyper masculine, no one could be given a chance to wonder if I was gay.
Thanks for the links Gary, I'll have a look at them.
I think you're also right about there not being any 'masculinity checklist' - I suppose most guys have their own ideas about what masculinity entails and try their best to live up to those expectations...it's probably what I'm doing right now, trying to figure out what it means for me. You also bring up a good point of victims of abuse, whether from sexual abuse or bullying or physical abuse, feel more pressured to prove their masculinity. I hadn't thought of it that way before, I always thought of it as regaining a healthy sense of natural masculinity that was lost...is there actually a line to distinguish these two ways of looking at it...?