Ganapati Muni, a great Siva bhakta, chose Tiruvannamalai, the holy seat of Siva, for his tapas in 1903 and briefly met Sri Ramana on the hill. In 1907, when he came again to Tiruvannamalai he found that nothing tangible had emerged from his severe tapas. Disappointed, he climbed up the hill and fell flat on his face holding Sri Ramana's feet with both hands. With a voice trembling with emotion he cried, "All that has to be read I have read. I have performed japa to my heart's content. Yet I have not up to this time understood what tapas is. Pray, enlighten me about the nature of tapas."
After listening to the Muni, Sri Ramana silently gazed at him as he sat in anxious expectation. Then he said in Tamil, "If a mantra is repeated and attention directed to the source from where the mantra-sound is produced, the mind will be absorbed in that. That is tapas." This short instruction filled Muni's heart with joy.
Source: Bhagawan Sri Ramana Maharshi - Jivan ane Sandesh by Yogeshwarji (Gujarati).
Taken from Shastri's Blog