The peace of the chitta (or mind) can be brought about through the practice of sympathy, tenderness, steadiness of purpose, and dispassion in regard to pleasure or pain, or towards all forms of good or evil.
The peace of the chitta is also brought about by the regulation of the prana or life breath.
The mind can be trained to steadiness through those forms of concentration which have relation to the sense perceptions.
By meditation upon Light and upon Radiance, knowledge of the Spirit can be reached and thus peace can be achieved. The chitta is stabilized and rendered free from illusion as the lower nature is purified and no longer indulged.
Peace (steadiness of the chitta) can be reached through meditation on the knowledge which dreams give.
Peace can also be reached through concentration upon that which is dearest to the heart.
Yoga Sutras of Patanjali