Be Calm and Be Happy.

There's a moment in your life when you feel that happiness,
that kind of emotion like you don't need anything else but.
I think it just happens once or twice in life.
Sometimes, people may not understand what you're feeling, so
you're the only person that can understand that feeling. People may
criticize about your happiness, but it doesn't matter. Why? Easy.
While you're happy and okay, everything's all right and that's the
most important thing - your own good.

Life has a lot of things, people, places, sounds, smells, etc. so
you must enjoy it.  Just avoid the bad thoughts of the other people,
laugh, relax, and the most important thing, be happy, that's all you need.
Nothing more than that, because if you're not happy, who's the one who'll
make you feel like that? You're the best person that can do that. It's like that
popular phrase in these days: keep calm and be happy.

[Your vocabulary and grammar are excellent, except for your organization of sentences.  Sometimes you put two complete unrelated thoughts in one sentence, separated by commas.  That's not too bad, though.  As I said, the rest is excellent.]