Bg 2.66

nasti buddhir ayuktasya
na cayuktasya bhavana
na cabhavayatah santir
asantasya kutah sukham

Word for word: 
na asti — there cannot be; buddhih — transcendental intelligence; ayuktasya — of one who is not connected (with Krishna consciousness); na — not; ca — and; ayuktasya — of one devoid of Krishna consciousness; bhavana — fixed mind (in happiness); na — not; ca — and; abhavayatah — of one who is not fixed; santih — peace; asantasya — of the unpeaceful; kutah — where is; sukham — happiness.

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
One who is not connected with the Supreme [in Krishna 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 by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Unless one is in Krishna consciousness, there is no possibility of peace. So it is confirmed in the Fifth Chapter (5.29) that when one understands that Krishna 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 Krishna 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 Krishna 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 Krishna is certainly always in distress and is without peace, however much he may make a show of peace and spiritual advancement in life. Krishna consciousness is a self-manifested peaceful condition which can be achieved only in relationship with Krishna.