This is the second of three articles about yoga practice. Lord Patanjali, in his yoga sutras, states that the yoga of action consists of tapas [the subject of my first article], Svadhyaya, and Ishvara Pranidhana [surrender of all actions to God]. Nowadays, no one has a still mind, and so we all perform action. The first sutra or verse of the second chapter tells how to do it. Svadhyaya is the second component, after tapas, required to transform action into yoga.
Whereas every action needs to be a tapas, helping to make your body and mind attain the purity of God, not every action needs to involve Svadhyaya. Svadhyaya is the ingredient in your actions needed to turn every action [tapas] into one conducted for the benefit of God [Ishvara Pranidhana].
Svadhyaya therefore includes study of the Scriptures so that you begin to understand the nature of your self and of God. Only then can your actions be effective in doing God's wishes. Lord Patanjali was in incarnation of God and therefore the yoga sutras themselves are a Scripture, or rather the Scripture for the yoga student. Svadhyaya includes counting the sacred mantra OM if and when this is done with a reflection on the qualities of God.
Svadhyaya includes all study that makes your actions [tapas] more effective in setting God. If you are a family man and earning money as a teacher physics in order to see your family, then your study of physics to keep abreast of developments is Svadhyaya. If your teaching is to provide luxuries to your family, it is not Svadhyaya. Learning yoga in order to teach yoga is not Svadhyaya: yoga is not learnt in order to teach.
Yoga is tapas.