So God realization means spiritual realization. So Ṛṣabhadeva says, tapo divyaṁ putrakā yena sattvaṁ śuddhyed (SB 5.5.1): by purification of your existentional condition you enjoy brahma-saukhyam. After all, we are searching after happiness, pleasure. So on account of our impure existential condition, our so-called happiness is temporary. Brahma-saukhyam means, here again, yena sattvaṁ śuddhyed, when your existence is purified. Now we have got impure existence, this material body. When we get our spiritual body, that is called purified.
So Ṛṣabhadeva says, sattvaṁ yasmād brahma-saukhyam anantam. As soon as you get your spiritual body, then there is unlimited happiness. We are, after all . . . in the Vedānta-sūtra it is said that the living entity or God, both of them are for enjoying life, blissful life. Just like when you are diseased, you have got some fever, so you cannot enjoy life. Similarly, in this diseased condition of material existence we, actually, we cannot enjoy life. Therefore, if we purify our existentional condition by tapasya, then we come into our spiritual existence and we can enjoy our life eternally. (break) . . . therefore, that when we have got this human form of life, we shall not waste it simply for sense gratification like the dogs and hog. We should practice tapasya, restrain, and then we purify our existence, and we are situated in a position wherein we can enjoy blissful life forever.
Now the process is prescribed how to execute this tapasya life.