Swami Sivananda had practised very intense sadhana, which may have no parallel in modern times. He had practised to perfection sadhana in various Paths of Yoga. Through this most intense sadhana, he attained the supreme Bliss, unalloyed Joy and eternal Happiness. And so he tries to awaken man from the slumber of ignorance and gives a call to attain that highest Experience through sadhana. This makes his instructions on sadhana all the more important. Here are some of his teachings on this subject...
Now is the time for you to start a spiritual life, not tomorrow.
Sadhana is any practice to steady the wandering mind and to fix it on God. He who does sadhana is called a sadhaka. Self-restraint, purification of the mind, cultivation of divine virtues, prayer, japa, kirtan, dharana or concentration, meditation is sadhana.
Introspect. Look within. Try to remove your defects. This is the real sadhana. This is the most difficult sadhana. You will have to do it at any cost. Removal of your defects needs a great deal of struggle for many years. Vicious habits will have to be rent asunder.
You must have a pure mind if you want to realise the Self. Unless the mind is set free and you cast away all desires, worries, delusion, pride, lust, attachment, likes and dislikes, it cannot enter the domain of supreme peace and unalloyed felicity or the Immortal Abode. Drive off all negative thoughts. Become positive always. Positive overpowers the negative.
Mind is compared to a garden. Just as you can cultivate good flowers and fruits in a garden by ploughing and manuring the land, and removing the weeds and thorns, and watering the plants and trees; so also you can cultivate the flower of devotion in the garden of your mind by removing the impurities of the mind, such as lust, anger, greed, delusion and pride, and watering it with divine thoughts. When the garden is clean, when there are no weeds and thorns, you can get good fruits. So also, when the mind is pure, the mind is free from lust, anger, etc., you can have the fruit of deep meditation. Therefore, cleanse the mind of impurities first.
Awake, Friends! Get ready for the holy communion. Start japa, kirtan, meditation, enquiry. How sweet is meditation! Hear the sweet music of the inner Soul.
Spiritualise all your activities. This is very important.
Have satsanga. Meditate. Enquire: "Who am I?" The ignorance will vanish. Brahma-jnana will dawn. Climb steadily and reach the peak of wisdom by intensifying dispassion and practising intense sadhana..
The two obstacles to Self-realisation are egoism and desire. Egoism is the most dangerous weakness of man. It brings downfall of the spiritual aspirant. The moment egoism comes in, there will be immediate blocking to the free flow of the Divine Energy. Therefore, slay this egoism.