Each form of life supports all others; together they weave the grand web of life. Thus there really is no happiness for oneself alone, no suffering that afflicts only others.
Life for everyone is a struggle against the sufferings of birth, old age, sickness and death. Happiness is not the absence of problems or worries; it is to be undefeated no matter what problems or worries we may face. And this happiness is not solely focused on oneself. Truly happy are those who can help others become happy.