Daily Reading: Bhagvad Gita As it is- Page-97

Bg 2.66

nāsti buddhir ayuktasya
na cāyuktasya bhāvanā
na cābhāvayataḥ śāntir
aśāntasya kutaḥ sukham

Translation: 

One who is not connected with the Supreme [in Kṛṣṇa consciousness] can have neither transcendental intelligence nor a steady mind, without which there is no possibility of peace. And how can there be any happiness without peace?

Purport: 

Unless one is in Kṛṣṇa consciousness, there is no possibility of peace. So it is confirmed in the Fifth Chapter (5.29) that when one understands that Kṛṣṇa is the only enjoyer of all the good results of sacrifice and penance, that He is the proprietor of all universal manifestations, and that He is the real friend of all living entities, then only can one have real peace. Therefore, if one is not in Kṛṣṇa consciousness, there cannot be a final goal for the mind. Disturbance is due to want of an ultimate goal, and when one is certain that Kṛṣṇa is the enjoyer, proprietor and friend of everyone and everything, then one can, with a steady mind, bring about peace. Therefore, one who is engaged without a relationship with Kṛṣṇa is certainly always in distress and is without peace, however much he may make a show of peace and spiritual advancement in life. Kṛṣṇa consciousness is a self-manifested peaceful condition which can be achieved only in relationship with Kṛṣṇa.

Bg 2.67

indriyāṇāṁ hi caratāṁ
yan mano ’nuvidhīyate
tad asya harati prajñāṁ
vāyur nāvam ivāmbhasi

Translation: 

As a strong wind sweeps away a boat on the water, even one of the roaming senses on which the mind focuses can carry away a man’s intelligence.

Purport: 

Unless all of the senses are engaged in the service of the Lord, even one of them engaged in sense gratification can deviate the devotee from the path of transcendental advancement. As mentioned in the life of Mahārāja Ambarīṣa, all of the senses must be engaged in Kṛṣṇa consciousness, for that is the correct technique for controlling the mind.