Okay here's a thing. Smile when you're happy, and cry when you're sad, and stop il-legitimising your emotions based on a quote that can so easily be taken out of context. Because someone has it better than you, too.
Of course there are people out there that truly have it worse than you, and the saying certainly aids in being self-aware, and not affluent. But at the same time, don't stop it from allowing you to feel whatever you are - even if afterwards, you acknowledge that it might have been kinda stupid.
That's all I really want to say.