Many have said love is an irrational idea. I would agree to the world love is irrational, infact we are born into a world where lust is one of the most rational things there is (so it is thought, and we are born into the world thinking lust is joy without knowing. Lust in this case is just a strong desire. Why is love irrational and lust rational? The reason, we live in a world where we the human think we are the center of the universe, I would have reason to believe serving my own desires is the most rational of rationals, until I realize His love is what saved me, then to me love becomes the greatest rational.
Lust is often a bad thing. Lust of food can easily turn to gluttony. Lust of money can become greed. Blood lust only breeds hate. However I think as a Christian I should lust for love. Not to recieve, but to give. To love someone is to say I am going to give of myself so I can be with you even in death I will give of myself to you my brother, or friend, as Christ did. To love is to say I will give of my time so I can see you through the circumstances. I would go on but you probably by now get the point.