“For self-realization, the people in Satya-yuga, living a lifetime of a hundred thousand years, were able to perform prolonged meditation. And in Treta-yuga, when the duration of life was ten thousand years, self-realization was attained by performance of great sacrifice. And in the Dvapara-yuga, when the duration of life was one thousand years, self-realization was attained by worship of the Lord. But in the Kali-yuga, the maximum duration of life being one hundred years only and that combined with various difficulties, the recommended process of self-realization is that of hearing and chanting of the holy name, fame, and pastimes of the Lord.” (Shrila Prabhupada, Shrimad Bhagavatam, 1.1.21 Purport)