Have u ever smiled without any joke or reason?Your answer must be NO but smile is very necessary for healthy life and mostly we can impress and win hearts by our smile.Once concentrate on any child,how he or she attracts us and how he or she make us ready to play with them? Our smile play a same role like this. Well make a habbit of smiling and be kind with each and everyone.
Enjoy your life :)
Pic copied from google images