Like Yama, Niyama also has five principles. They are: Shoucham (purity), Tapas (penance), Santosham (happiness/satisfaction), Swadhyayam (study of Divine literature), and Ishwara Pranidhanam (contemplation on God).
Purity is two-fold: internal and external. External purity is attained through water and soil. All the parts of the body should be clean. Daily ablutions are not only for the sake of health but also for general happiness. You should also try to keep the surroundings and the environment clean. External purity is not limited to the body alone. It includes everything that we use in our daily lives such as clothes, mattresses, books that you study, the house that you stay in, etc. Next is internal purity. The mind becomes impure because of lack of love and increasing hatred. Evil thoughts further pollute the mind and pure thoughts can’t find a place in a polluted mind. Hence, to purify the mind one should develop pure qualities such as love, compassion, pity, patience, etc.
Penance does not mean turning the body upside down with the head below and legs towards the sky. Penance is constant contemplation, in thought word and deed, on the goal that you have set. You should always think of the goal that you wish to achieve. Hence it is said, ‘Satatam Yoginaha’. You should crave to achieve the attributeless, formless aspect of Atma. Such craving transforms into penance. There should be unity of thought, word and deed. This is contemplation on God. The attributeless, formless Divinity can be attained through such penance. Penance does not imply leaving the society and going away to forests, living on leaves and tubers and wasting life.
Penance is distancing oneself from evil thoughts. It does not mean leaving your wife and property and going away to forests. It is renouncing bad thoughts. That is communion. That is sacrifice. Purifying the heart with such pure thoughts is called penance.
When does one attain happiness? Man feels happy when he is contented. As desires multiply, dissatisfaction increases and man’s worries start mounting. Hence you should be contented with what you have. You should feel happy with what you have gained. You should not entertain excessive desires. Man feels happy only when he is contented. He, who is satisfied, is the richest man. Hence you should be contented. You gain happiness only through contentedness.
It is not just learning the Vedas. You should also recite the Bhagavad Gita, Upanishads and the Brahma-Sutras (the three constitute the Prasthana Trayam). You should also get acquainted with religious scriptures. You should keep studying one or other religious texts. Thus you can eliminate some of the impurities accumulated in the mind.
The last among the values in Niyama is Ishwara Pranidhanam (contemplation on God). All the activities one undertakes should be pleasing to God. For every activity that one does one should consider if it pleases God or not, if God feels happy about it or not. God is your own conscience. You should not do that which is not acceptable to your conscience. You heart punishes you. Your mind condemns acts which are not acceptable to your conscience. Therefore, undertake acts which are in accordance with your conscience. This has been termed in Vedanta as ‘Sarva Karma Bhagavat Preetyartham’ – All activities have to be undertaken to please God. Only such acts will give good results. Yama and Niyama sanctify Dharma, Artha, Kama and Moksha (righteous actions, righteous wealth, righteous desires and liberation). Then alone does one attain the merit of undertaking meritorious deeds such as Sama (appeasing) and Dama (subjugating).