Senyum is the Indonesian word for Smile/미소/微笑み/微笑: The expression that you have on your face when you are happy, amused, etc. in which the corners of your mouth turn upwards. ~ Oxford Advanced Learner’s Dictionary.
A smile is a curve that sets everything straight. ~ Phyllis Diller
A smile is an inexpensive way to change your looks. ~ Charles Gordy
If you smile when no one else is around, you really mean it. ~ Andy Rooney
Even if the smile looks silly, it is a smile, it is the intention that matters. Smile is like an unspoken language. People take smile for granted, from medical perspective, being angry or not happy can actually shorten our lifetime, a smile can cool down our mind.
A smile can be spontaneous or artificial. The artificial one looks awkward. Try your best to smile spontaneously. Let those muscles move!