Says Shri Krishna:
मनः प्रसादः सौम्यत्वं मौनात्मविनिग्रह: |
भावसंशुद्धिरित्येतत्तपो मानसमुच्यते || (भगवद गीता : १७ : १६ )
Manah prasadah saumyatvam mounatmavinigrahah |
Bhavasamshuddhirityetattapo manasamuchyate || (bhagavad gita: 17: 16)
Serenity of mind, good heartedness, silence, self-control, purity of nature are together called ‘mental austerity’.
यज्ञदानतपःकर्म न त्याज्यं कार्यमेव तत् |
यज्ञो दानं तपश्चैव पावनानि मनीषिणां || (भगवद गीता : १८ : ५ )
Yagnadantapahkarma na tyajyam karyameva tat |
Yagno danam tapaschaiva pavanani maneshinaam || (bhagavad gita: 18: 5)
Acts of charity, sacrifice and austerity should not be abandoned. Worship, charity and austerity purify even the purest.
Mind becomes mighty when it is serene, silent, pure and well managed. There is no exception/exemption to this. We must reduce the quantity of thoughts in the mind and increase its quality. We can see the depths of our personality unfold by sacrificing our weaknesses, giving in charity large heartedly, without grudge or pride. This mental austerity brings about a brilliant discipline within and creates conditions under which alone, the highest spiritual unfoldment is made possible.
Swami Chinmayananda says,” as your body requires cleansing, so does your mind. So long as your mind is full of negative tendencies, you can never bring it to single-pointed concentration. Control the mind.”