From 3 chapter of Autobiography of a Yogi:
Swami Pranabananda:
“I used to meditate with another disciple for eight hours every night. We
had to work at the railroad office during the day. Finding difficulty in
carrying on my clerical duties, I desired to devote my whole time to God.
For eight years I persevered, meditating half the night. I had wonderful
results; tremendous spiritual perceptions illumined my mind. But a little
veil always remained between me and the Infinite. Even with super-human
earnestness, I found the final irrevocable union to be denied me. One
evening I paid a visit to Lahiri Mahasaya and pleaded for his divine
intercession. My importunities continued during the entire night
“‘Angelic Guru, my spiritual anguish is such that I can no longer bear my
life without meeting the Great Beloved face to face!’
“‘What can I do? You must meditate more profoundly.’
“‘I am appealing to Thee, O God my Master! I see Thee materialized before me
in a physical body; bless me that I may perceive Thee in Thine infinite
form!’
“Lahiri Mahasaya extended his hand in a benign gesture. ‘You may go now and
meditate. I have interceded for you with Brahma.’
“Immeasurably uplifted, I returned to my home. In meditation that night, the
burning Goal of my life was achieved. Now I ceaselessly enjoy the spiritual
pension. Never from that day has the Blissful Creator remained hidden from
my eyes behind any screen of delusion.”
From 13 chapter of Autobiography of a Yogi:
Yogananda:
"Sir, have you not been singleheartedly seeking God for a long
time?"
Ram Gopal Muzumdar:
“I have not done much. Behari must have told you something of my life. For
twenty years I occupied a secret grotto, meditating eighteen hours a day.
Then I moved to a more inaccessible cave and remained there for twenty-five
years, entering the yoga union for twenty hours daily. I did not need sleep,
for I was ever with God. My body was more rested in the complete calmness of
the superconsciousness than it could be by the partial peace of the ordinary
subconscious state.
“The muscles relax during sleep, but the heart, lungs, and circulatory
system are constantly at work; they get no rest. In superconsciousness, the
internal organs remain in a state of suspended animation, electrified by the
cosmic energy. By such means I have found it unnecessary to sleep for years.
The time will come when you too will dispense with sleep.”
From 21 chapter of Autobiography of a Yogi:
I knew an Indian saint, half of whose body was once festering with sores. His diabetic condition was so acute that under ordinary conditions he could not sit still at one time for more than fifteen minutes. But his spiritual aspiration was undeterrable. "Lord," he prayed, "wilt Thou come into my broken temple?" With ceaseless command of will, the saint gradually became able to sit daily in the lotus posture for eighteen continuous hours, engrossed in the ecstatic trance.
"And," he told me, "at the end of three years, I found the Infinite Light blazing within my shattered form. Rejoicing in the joyful splendour, I forgot the body. Later I saw that it had become whole through the Divine Mercy."
From 26 chapter of Autobiography of a Yogi:
The scriptures aver that man requires a million years of normal, diseaseless evolution to perfect his human brain sufficiently to express cosmic consciousness. One thousand Kriya practiced in eight hours gives the yogi, in one day, the equivalent of one thousand years of natural evolution: 365,000 years of evolution in one year. In three years, a Kriya Yogi can thus accomplish by intelligent self-effort the same result which nature brings to pass in a million years. The Kriya short cut, of course, can be taken only by deeply developed yogis. With the guidance of a guru, such yogis have carefully prepared their bodies and brains to receive the power created by intensive practice.
...
The body of the average man is like a fifty-watt lamp, which cannot accommodate the billion watts of power roused by an excessive practice of Kriya. Through gradual and regular increase of the simple and "foolproof" methods of Kriya, man's body becomes astrally transformed day by day, and is finally fitted to express the infinite potentials of cosmic energy-the first materially active expression of Spirit.
From the book of sayings of Paramahansa Yogananda "The Essence of Self-Realization"
If you want to be a Master in this lifetime, then, along with your other meditation practices, practice Hong-Sau at least two hours a day. As a boy, I used to practice Hong-Sau sometimes for seven hours at a time, until I entered the breathless state of ecstasy.
Paramhansa Yogananda