Like your weight set-point, which keeps the scale hovering around the same number, your happiness set-point will remain the same unless you make a concerted effort to change it.

So the difference between most books about love and Love For No Reason is that traditional love books focus on love as a stream of energy between two people, whereas this book focuses on love as a deep state of being that you can live in no matter what's going on in your life.

The basis of all love is self-love and we certainly suffer a lot in our society from lack of self-love. When we don't take care of ourselves, it's really just a symptom of not loving ourselves. So the worst thing that we can do is to beat ourselves up for how we've already treated ourselves.

There's a wonderful support network developing worldwide of people who understand what this big calling is, the calling of love. People often ask me, "Is it selfish to want to experience more love? Aren't you just focusing on yourself?" and my answer is that it's the least selfish thing you can do. When you start living more and more in higher states of love, it affects everyone around you and it's the biggest way you can contribute to this planet.

HeartMath found that five minutes of feeling love and care can strengthen your immune system for up to six hours, whereas five minutes of feeling angry can weaken and suppress the immune system for six hours. Love releases very powerful, beneficial chemicals into the body.

The concept (of happiness) is universal. In Buddhism, it is called causeless joy, in Christianity, the kingdom of heaven within, and in Judaism it is called ashrei, an inner sense of holiness and health. Is Islam it is called falah, happiness and well-being, and in Hinduism it is called ananda, or pure bliss.

So, in life we have a one question final exam - and it's not the kind of exam you can cram for at the very end. One of the main reasons we're alive is to expand our capacity to love.