Sometimes when you feel bore, you need "something" that can make you feel better. Sometimes, "something" that can make you feel better is crying. Sometimes when you cry, you never know why you are crying. Sometimes, people had judged that crying is one of the sign of weakness, whereas actually your tear can changes the situation, it can changes your feeling, thats why some people prefer to cry when they're show something like happy and unhappy too.
So, who can prohibit you to cry? if that can change your mood? why not? but after that, dont forget to spread your smile again, because world always wait YOUR SMILE :)
