It's important to behave in a sensible way, like an adult, in order to be able to take the right decisions... However, what matters for me is to have a real magnetic personality; to have a strong character that makes me noticeable. And it's not necessary to be so serious and sensible in order to be successful or noticeable. You can be a mixture of both - childish and sensible. I believe that everything we do or say is reflective of our personality, that's why I prefer to act and behave spontaneously.
'Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.' ~Dr. Seuss