How do you stop yourself from crying?

If you want to cry, but you know you shouldn’t, or know that you don’t have a good enough reason, how do you stop yourself?
I would really like to cry right now from news I just received, but the news isn’t a good enough reason to cry. It was nothing bad, just something personal that makes me sad knowing I’ll never do, but I can feeling a crying fit brewing literally brewing inside me, but I know I shouldn’t cry for this because there is much worse to be sad about. How do I stop myself from crying?