I don't think "being a man" is really a subject you can pin down. Everybody has their own definition of it. All I can give is my own view of what it means "to be a man." You do your job, whatever it may be, however hard it will be. You don't procrastinate on it. You don't whine about it. You don't brag about it. You do it, and you go home.
At some point in your life, you're going to cross paths with somebody who is going to depend on you. It doesn't matter who they are or what the situation is. It's your job not to let them down. It's your job and responsibility to be there when they need you the most.
I see that a lot of people base themselves as men because they're physically strong. The macho routine. Inflated egos. I base being a man as none of that. You don't need only physical strength. You use your head. You be kind to people only as far as you can allow it without them stepping on you or taking advantage of you. Know when to draw the line on things, whether it be people, or your own limits.
You have physical limitations. Know the difference between when you can do it alone and when you need help. You have emotions. There's a time and a place for all of them. Lastly and most importantly. Acknowledge that you are, like anybody else, just a human being.