smile and the world smiles with you, cry and you cry alone

Smile and the world smiles with you, cry and you cry alone refers to the fact that those who smile and keep a positive dispotiion wil naturally allow other people to feel positive in the same setting or about the same things. However if you are negative (such as crying or whining) nobody will want to be around you for that. The statement shows that people want to be around other positive and optimistic people.