A worldly-minded person is a prey to sexual thoughts and thoughts of hatred, anger and revenge. These two types of thoughts actually take possession of his mind. He is a slave to these two sets of thoughts. He does not know how to divert his mind and fix it on some other good, noble thought. He does not know the laws of thought.
He is quite unaware of the nature and subtle workings of the mind. His position is extremely deplorable despite his earthly possessionsand bookish knowledge obtained in universities. Viveka has not awakened in him. He has no Sraddha in saints, Sastras and God. He is unable to resist an evil desire, craving or temptation on account of his weak will. The only potent remedy to remove his world-intoxication, world-charm, world-delusion is constant… association with Sadhus, Sannyasins and Mahatmas.
After retirement, everybody should have a background of thought and should spend his time in philosophical studies and divine contemplation. Old habits of loose thinking must be replaced by cultivating fresh habits of good thoughts. At first, a tendency to think of good thoughts will be formed. By continued practice, a positive definite habit of thinking of virtuous, helping thoughts will be developed. You will have to struggle very hard. The old habits will try to recur again and again. Till you are firmly established in the habit of thinking of good thoughts only, you will have to fill the mind again and again with Sattvic thoughts, divine thoughts, thoughts of the Gita, Lord Krishna, Lord Rama, the Upanishads, etc. New grooves and avenues will be formed now. Just as a gramophone-needle cuts a small groove in the plate, Sattvic thinking will cut new, healthy grooves in the mind and brain. New Samskaras will be formed.
(pg. 172, “Conquest of Mind” by Swami Sivananda)