Sattva is the highest of all gunas. It is synonymous to purity, knowledge and joy.  Rajas whereas is the principle of aspiration, enthusiasm, longing and restlessness and Tamas is the lowest of all gunas, it leads to inertia (inaction), anger, lifelessness and delusion. When, a reference of a calm composed mind is made, a predominance of Sattva is what is being referred to.

It is extremely difficult to control the mind. Hence no failure should not be taken seriously and no success as final. Failures, instead should be spurs to more determined, sustained and intelligent efforts.  Through continous Practice and Detachment , Mind controlled is possible and every doubt to the contrary must be ignored.

Though the Mind seems to cognize but it is not the cognizer, it is not the source of light even if it seems luminous. It borrows its radiance from the Self (Atman) and acts just as an internal instrument (Antahakaran) for it. It is through mind, the Self i.e. Atman or pure consciousness, that is free and eternal, apprehends and responds to the external world.

Ethical life cannot be a substitute for spiritual awakening as it is only the basis for consciousness to evolve. For Yoga to happen, Body and Mind must be truly refined. This highest experience calls for the highest level of effort and there are many paths towards it.  

Yoga is the technique to arrest our awareness and gradually bring it from the state of being disturbed and being all over the place to gradually becoming calm , focussed and ultimately concentrated. All individual efforts and actions which help one become concentrated are nothing but the activities of Yoga.