I am 41, too. Just my opin, but the acting and feeling 13 is a pretty good place to start.
I find myself back at 8 (age of abuse) for a lot of this stuff, that is the point I usually (still) have to go to start to work things through.
But in your case . . . I mean a 13 year-old in a locker room with men . . . any 13 year old would be thinking "Who is hairiest? Who is (or not) circumcised? Who is biggest?" Geeezzz, no wonder your mind is saying get me out of here, get me out of here.
I think you are pretty normal.
- - - - - - - - -
But as far as proper manly behaviors, Yeah, you could learn them, but I can?t really recommend it.
I learned to fake all the proper manly behaviors exceptionally well.
Worked in farming, construction, was an army troop, and then a combat arms officer, construction engineer with a four-wheel truck. If anyone wanted to mess with me, I would go to the manly-handbook, and come back the routine of "I?ll rip your head off and sh*t down your throat." (page 206 of the manly-behavior handbook
Even when my ever-so-versatile all manly-behavior totally failed me and my brains melted-down, and I wound in an (all female) on-line therapy group, I was still stuck in it. I was jerky and "manly" to point that I got kicked out. I was just a wreck from that. It was maybe the most traumatic thing I had to go through in this recovery stuff.
But when any of the guys at work would ask -- How is your therapy group?
You know my answer -- back to the routine ? "smoke, joke and be cool." (page 185 of the manly behavior handbook
I would slowly smile and meet everyone's eyes and say, "Well, things are not going that great. I got kicked out of my all women?s therapy group."
Everyone would just fall on the floor laughing. And I would laugh instead of cry.
Not smart for my heart. Here is the real deal. I had to un-learn all those manly things, and I can finally (usually) just be me. And it turned out I like that ok.
Again, just my opinion -- just be yourself, be kind to yourself, and be well.