The more we take the welfare of others to heart and work for their benefit, the more benefit we derive for ourselves. This is a fact we can see. And the more selfish we remain and self-centered, the more selfish our way of life is, the lonelier we feel and the more miserable. This is also a fact we can see.
The belief that unhappiness is selfless and happiness is selfish is misguided. It's more selfless to act happy. It takes energy, generosity, and discipline to be unfailingly lighthearted, yet everyone takes the happy person for granted. No one is careful of his feelings or tries to keep his spirits high. He seems self-sufficient; he becomes a cushion for others. And because happiness seems unforced, that person usually gets no credit.