Why is it so hard for some people to just be themselves?

I think that some people have a hard tie being themselves because they are not comfortable with who they are. Self confidence can be quite a deterrent when you have to show yourself to the world. it is easier to hide from who you are then just to be yourself.

If you are being with friends and partner, it is fine to be yourself except some of your bad habits should be improved. but if you are with your superior, business partner etc, you would need to picture a good image to them in order to be successful in career. You can't just be the normal self wearing shorts and shirts to work in a firm. you need to dress yourself up to show professionalism. Again, it depends on the situation ^_^

you have to go back centuries my dear

Maybe because they still haven't realize who really they are. :( Sad but true. Especially if that person is in the age between 12-20 yrs.old. They are still searching & finding their selves. Sometimes, other person also play a big role in finding ourselves. A stranger, a vendor, a driver, or a friend may touch your life, and so do you, then later on you will realize if who really you are/what you want in life. Being ourselves/being who really we are is not easy as 123. It requires patience, understanding (from our parents & friends), & learning. Even me, I'm 22 years old, and yet I'm still confused if what job I really want (even though I've already finished my degree). Being ourselves is a continuous process. You have reached your dreams, but later on you will fall again into what we called cross roads. But, if you have already know your self, what you want, what you hate, & whom you love, I think things will go smoothly. (I think) :D

People tend to try to be something there not to try to impress others, The best thing you can do is be yourself and if they don't like it OH Well, I Love Being Me!!