1. Smiling helps keeping your skin healthy. To smile you have to make your facial muscles work, a simple way to avoid wrinkles and look younger!
2. People do their best when their colleagues/bosses/schoolmates smile. When you are working and people around you smile, you get relaxed and you can concentrate easier. On the opposite, if everyone around you is nervous, you'll surely get nervous too.
3. Tourists like cities, where friendly people live. Smile to make your country look more attractive!
4. No one can think positively about life when people around him are sad. Smile to give unlucky people a reason to smile.
5. Don't let people hurt you! The best thing you can do to discourage your enemies is smiling. If someone tries to make you upset you don't have to start a war to make him feel bad. Just smile! He would get frustrated and stop annoying others.
6. Smiling helps you find your true love because it makes you more attractive for your (potential) partner. No one likes people who always look angry.
7. Smiling save others. If a taxi driver is rude towards you, smile at him! He probably had a bad day and your smile will make it better. This way he won't be rude towards next costumers and they won't go home angry and shout at their children.
8. Smiling makes you beautiful. It's proven. When you smile sincerely you irradiate light from your eyes and people find it lovely. How many people have you heard saying "he's not handsome, but I can't resists his smile!"? Don't be selfish! Smile for the sake of people's eyes!
9. Smiling is a great way to say "Thank you for being here" to all your darlings. Don't forget to smile when you meet them, otherwise you would look ungrateful and upset them.
10. Everything is expensive in this world. Smiling doesn't cost anything, take advantage of it!