Okay, you asked for the secret of life? Here it is -- well, not the secret of life, exactly, but the secret of living meaningfully.
I have heard it said,
Man and the world are not separate. Every action we take affects the world in some way. We do not live in a vacuum; everything in life is interrelated.
Man has the distinction of being able to make choices in his actions. We can choose to act positively or negatively, in order to affect the other aspects of the world for better or for worse. The wise person will make choices based on respect of this law, and of the other beings (and so-called non-beings) in the world. If we simply act with respect, and a concern for making choices that benefit the world as a whole, happiness will increase. That is guaranteed.
I have tried not to make this preachy, or sutra-like, but the truth of it is obvious. Act with carelessness and the world becomes sloppy. Act with anger and the world becomes hostile. Act with kindness, and the world becomes gentle and friendly. It can be seen in everything we do. Sometimes it takes time for an action to generate a reaction, but eventually it will, and the world (and you) will reap the benefit, or suffer the consequences.
See the world as your friend and ally, and don't disrespect it. It will be good to you in return.