Today is the feast of St. Juan de Avila, Doctor of the Church. From one of his letters:
Oh tepidity! If those who give way to it only rightly understood what it is, they would less easily fall victims to it, for they would dread to become the slaves of so cruel a tyrant. If we are free from this vice, nothing we can do or suffer for God, even death itself, seems too great a burden, whereas the victim of tepidity finds a straw too heavy for him to carry. vice ruins a man's spiritual life, and it not only stops all perseverance in the good he had commenced, but even causes him to repent of having begun it, thus turning into bitterness what should be sweeter than honey to his soul.
The Israelites who journeyed through the desert had appetites so disordered that they could not enjoy the manna "containing in itself all sweetness," which God sent them. Their blindness was so great that they did not find fault with themselves, or with the evil condition of their health, but with the food, which was of the most savoury kind. They asked for some other sort of viand with which they thought they would be better satisfied and pleased:-it was given them, but at the cost of their lives. We are to learn by this that even if the things of God are not always agreeable to us, still we must not wish for what is contrary to them, however delightful it may seem to us, for without doubt it would poison our souls. We should rather rid ourselves of the disgust we feel for religion, and then, when the appetites of our soul are healthy, we shall feel a right and pleasant relish for the food God gives His children.
[St. John of Avila, from Letters of Blessed John of Avila, pp. 90-91.]