Let the wise guard their thoughts, which are difficult to perceive, extremely subtle, and wander at will. Thought which is well guarded is the bearer of happiness.
When you have read the Bible, you will know it is the word of God, because you will have found it the key to your own heart, your own happiness and your own duty.
It must not be supposed that happiness will demand many or great possessions; for self-sufficiency does not depend on excessive abundance, nor does moral conduct, and it is possible to perform noble deeds even without being ruler of land and sea: one can do virtuous acts with quite moderate resources. This may be clearly observed in experience: private citizens do not seem to be less but more given to doing virtuous actions than princes and potentates. It is sufficient then if moderate resources are forthcoming; for a life of virtuous activity will be essentially a happy life.
A child can teach an adult three things: to be happy for no reason, to always be busy with something, and to know how to demand with all his might that which he desires.
It is a curious sensation: the sort of pain that goes mercifully beyond our powers of feeling. When your heart is broken, your boats are burned: nothing matters any more. It is the end of happiness and the beginning of peace.
Consciously or unconsciously, every one of us does render some service or other. If we cultivate the habit of doing this service deliberately, our desire for service will steadily grow stronger, and will make, not only for our own happiness, but that of the world at large.
The hour when you say, "What does my happiness matter? It is poverty and filth, and a wretched complacency. Yet my happiness should justify existence itself!
If Allah has written for you happiness, no one can steal that from you, and if He has written for your heart to break, then no-one can mend it but He, so always put your trust in Allah.