He went away sad...

Sloth is defined by St. Thomas Aquinas as sadness in the face of some spiritual good which one has to achieve. The Catholic Encyclopedia's entry on sloth goes on to state: "A man apprehends the practice of virtue to be beset with difficulties and chafes under the restraints imposed by the service of God. The narrow way stretches wearily before him and his soul grows sluggish and torpid at the thought of the painful life journey. The idea of right living inspires not joy but disgust, because of its laboriousness."

This sadness is noted in the story of the young rich man:

... The young man saith to him: All these I have kept from my youth, what is yet wanting to me? Jesus saith to him: If thou wilt be perfect, go sell what thou hast, and give to the poor, and thou shalt have treasure in heaven: and come follow me. And when the young man had heard this word, he went away sad... (Matthew 19:16-22)

The Handbook of Moral Theology by Prummer lists some of the evil results of sloth: tepidity to the divine precepts, wandering towards what is forbidden, faint heartedness, and despair of salvation. The remedies given are: consideration of the evil results of this vice, meditation on man's eternal reward.