In the Bhagavad Gita, Lord Krishna says, "Manah Prasadah (cheerfulness and serenity), Saumyatyam (gentleness), Maunam (silence), Atmavinigraha (control of senses) and Bhava Samshudhi (elevated feeling of the heart) - these are called the austerity of the mind."
Manah prasadah means to allow the mind to be joyous. People who have been accustomed to think of austerity as something crude will be surprised by this. In Yoga philosophy, austerity is not supposed to give you pain, but discipline you so that the spirit flows in a healthy, unobstructed way through your personality. Thus, the effort to maintain cheerfulness of the mind is a dynamic aspect of austerity.
The next aspect of austerity is saumyatyam (gentleness). When you confront a situation that provokes your mind into becoming agitated or negative, simply look at it without building up ill will towards anyone.
When you watch a movie, you are always aware that all the happenings on the screen are more appearances. Therefore, though you feel sorrow at the tragic developments, you are not deeply affected in your heart. Similarly, be a spectator to your mind and its changes, and know that faith in God will ultimately make you truly gentle.
The next practice relating to the mind is mauna (silence). If you watch your mind, you will notice that a great many thoughts enter it constantly - so many in fact that, after a while, it is as if a lively discussion was going on deep in your mind.
When you are engaged in various action, watch your mind. Do not entertain conflicting thoughts and do not allow the mind to be agitated. The thoughts of the mind should be as still as a lake without waves. You can do this by turning your mind toward God and practicing japa.
The next austerity of the mind is called bhava samshudhi: Bhava means feeling. You must learn to watch your feelings and observe the types of feeling you hold within your heart. Develop the quality of grasping that which is positive in others so that your feelings is always magnanimous. Do not draw to yourself the negative qualities of others.
You must understand how much you are hurting yourself when your mind continuously focuses on the negative in others. Why not change your attitude? Look at any person and realize that God is shining through his eyes, that the Divine life-force is pulsating through him.
In a provocative situation, people tend to commit these three errors: physical involvement, bitter words and ill will. In the plan of yogic austerity, first learn to restrain the body, no matter how agitated you may be. Then you strive to control the speech, and finally you will succeed in controlling the ill of your mind.
Whoever practices this plan of austerity becomes a blessing for himself and for humanity. All that is good, beautiful and divine is possible through austerity alone.