Often we feel like we have to act in a 'normal'/'accepted' manner, though that may not be our true nature. When we do that, we can feel uncomfortable in this mask that we wear. The conscious effort also drains our energy, which can be better used elsewhere. Therefore, isn't it easier to stand up against what you perceive to be 'norms', and simply be yourself?
Let me give an example. In a field such as scientific research, being critical of other people's work is an important skill. However, some people take it too far by becoming cynical. For a long time, I interacted with quite a number of individuals who were not only cynical about other researchers' work, but all aspects of life as well. Even though my own personality focuses more on seeing the good in things, I felt a need to 'fit in', and picked up the habit of being cynical myself, not just at work but also in life sometimes. I thought that was the way to excel. However, I always ended up with a bad taste in my mouth, and felt uncomfortable on a subconscious level. I eventually became less enthusiastic at work, as it became mentally draining, a sign I took as a mismatch in interests. Just recently though, I brought up this 'problem' to a good friend, that I was doubting my path in science because I could never be truly critical, as I was more adept at seeing the potential, rather than shortcomings, in others' work. My friend asked, 'Why is that a problem? Why not treat it as a strength?'. As I mulled on his question, I recognized the source of the cynicism that was making me uncomfortable in my own skin, and weaned myself of this poisonous 'habit'. Being able to act naturally, I now feel so much better and lighter in my own being. I no longer feel bad if I am too positive or idealistic (within reason), and I feel happy about it. Being able to act in my true nature gives me more energy to focus on what is important, instead of trying to be something I am not.
So, why not be yourself? If you want to do something, go ahead and do it your way! If you want to randomly laugh at something silly, laugh! Who cares what other people think? (Don't act like a maniac though, of course.) They are not you, and they might not understand you, but you only have one life, and do you really want to live it as someone you are not?
Life is a dance you choreograph. Be brave, dance like nobody's watching =)