Bhagavad Gita Verse 14, Chapter 12

santushtaha satatam yogee yataatmaa dridhanishchayaha |
mayyarpitamanobuddhiryo madbhaktaha sa me priyaha || 14 ||
 
The yogi who is always contented, self controlled, with firm conviction, who has dedicated his mind and intellect to me, he who is such a devotee of mine is dear to me.
 
santushtaha : contented
satatam : always
yogee : yogi
yataatmaa : self controlled
dridhanishchayaha : firm conviction
mayi : to me
arpita : dedicated
manobuddhihi : mind and intellect
yaha : he who
madbhaktaha : my devotee
saha : he
me : me
priyaha : dear
 
Most of us derive contentment from people, objects and situations in the world, most notably after consuming a delicious meal. Contentment is a state where the mind does not want anything else from the world. But, this state is temporary because the contentment has been triggered by something that is temporary and finite, like food for example. Shri Krishna says that the yogi, the perfected devotee, derives contentment from Ishvara within himself, therefore he does not need to become a bhogi, one who runs after material objects for contentment. He is “satatam santushta”, even contented.
 
Another quality of a perfected devotee is a firm conviction that only Ishvara exists, and that the world does not exist independently of Ishvara. Most of us assume that the world has an independent existence. We attach all sorts of values to it. causing our intellect to generate innumerable goals and convictions around those values. The perfected devotee sees only Ishvara everywhere, and therefore is ever steadfast in his conviction that only Ishvara exists.
 
This “dridha nishchaya” or firm conviction is demonstrated by the devotee’s submission of mind and intellect in Ishvara, and also, the control of the mind, body and senses. When the intellect is convinced that only Ishvara exists, and when the mind thinks only of Ishvara, the devotee does not need any other special yogic technique to control the organs of action and the sense organs. Selfish desires are the cause of the mind, body and senses deviating from prescribed actions. When there is only the desire for Ishvara, they can never deviate. Shri Krishna says that the perfected devotee is a “satatam yataatmaa”, one who has complete self control at all times.
 
Here Shri Krishna concludes the line of thought that he began in the previous shloka by asserting that the devotee who has inculcated these traits is very dear to Ishvara. These eight shlokas starting from the thirteenth shloka are one of the most famous and beloved shlokas in the Gita.