“From beginningless time you have been conditioned to believe that the wonders of cyclic existence are sources of happiness, and you have habitually projected upon them a false image of beauty. But if, as a remedy, you train yourself to meditate on suffering and unpleasantness, you will put an end to these wrong ideas. Candramogin says that if you neglect to meditate on these, ignorance and attachment will increase, and you will continue to fuel the process of cyclic existence. Hence, it is vitally important to meditate on the faults of cyclic existence.”
From The Great Treatise on the Stages of the Path to Enlightenment by Je Tsong Khapa
As translated in: The Great Treatise on the Stages of the Path to Enlightenment: The Lam Rim Chen Mo by Tsong Khapa. Translated by the Lamrim Chenmo Translation Committee. Snow Lion/Shambhala Publications.