Smile!
Who would like you if you don't? Nobody likes sad people.
Smile!
Hide your troubles! They're nobody's concern. Everyone has their own things to worry about, so don't be selfish and don't pour yours into the mix as well.
Smile!
Tell them you're fine if they ask. You're fine. People in Africa are starving, millions of homeless freeze to death every year, cancer kills children every second. How can your problems possibly be more important than that? You're fine.
Smile!
And make yourself useful! Your wheeping helps nobody. Get your shit together! Do something! Appear normal at all cost, and most importantly...
Smile!