Bhagavad Gita Verse 57, Chapter 18

chetasaa sarvakarmaani mayi sanyasya matparaha |
buddhiyogaamupaashritya macchitaha satatam bhava || 57 ||
 
Mentally surrender all actions to me, designate me as the supreme goal, fix your mind on me by depending upon the yoga of intellect.
 
chetasaa : mentally
sarvakarmaani : all actions
mayi : to me
sanyasya : surrender
matparaha : me as supreme goal
buddhiyogam : yoga of intellect
upaashritya : depending upon
macchitaha : mind fixed on me
satatam : always
bhava : make
 
Shri Krishna summarizes karma yoga and bhakti yoga in this shloka. As we saw in the previous shloka, we need to continue performing our duty, and not to worry too much if we inadvertently perform a prohibited action, and to consider Ishvara as the one and only one aashraya, the ultimate refuge. How does this actually work in practice? A step by step approach towards karma yoga and bhakti yoga is enumerated in this shloka for the convenience of the seeker.
 
First, the seeker should fix Ishvara as his ultimate goal. This is mat paraha, one who is completely oriented towards Ishvara. Next, such a seeker should surrender all his actions to Ishvara. In the ninth chapter, Shri Krishna had said - whatever you do, whatever you consume, whatever you offer or donate, and whatever penance you perform, submit it to me. This is sarvakarmaani sanyasya. Nothing is done for selfish ends such as wealth, power, position, vanity and so on. All is done for Ishvara only.
 
Now, when the seeker faces challenges in life, he needs to have a method to deal with them. Equanimity is the answer. All actions are performed with full awareness and knowledge, as an offering to Ishvara. No action is perform haphazardly. Once the action is complete, the seeker should neither be attached to success, nor to failure. Such an attitude will only develop as a result of accepting every object, person or situation encountered in life as a gift or a praasada from Ishvara. This is buddhi yoga, as described in the second chapter.

Bhagavad Gita Verse 6, Chapter 12

ye tu sarvaani karmaani mayi sanyasya matparaahaa |
ananyenaiva yogena maam dhyaayanta upaasate || 6 ||
 
But, those renounce all actions in me, intent upon me only, meditate upon me through the single-pointed yoga of worship..
 
ye : those
tu : but
sarvaani : all
karmaani : actions
mayi : me
sanyasya : renounce
matparaahaa : intent upon me
ananyena : single-pointed
eva : only
yogena : through yoga
maam : me
dhyaayanta : meditating
upaasate : worship
 
Previously, Shri Krishna compared seekers who worship the formless Ishvara to those who worship Ishvara with form, and concluded that the worshippers of the formless Ishvara have more difficulty. We used the example of a child helping his parents to understand the attitude of the formless worshipper and the example of the worker helping his CEO exemplifying the worshipper of Ishvara with form. Now Shri Krishna re-emphasizes the qualifications of the worshipper of Ishvara with form, which is the route that most of us will take.
 
First, we have to renounce all our actions to Ishvara, in other words, practice karma yoga. Typically, when we perform any actions, we are looking for a tangible material result (monetary profit), emotional result (happiness) or an intellectual result (satisfaction). If our actions don’t turn out as we anticipated, we may get opposite results in the form of loss, sorrow or dissatisfaction. When we perform actions for the sake of renunciation to Ishvara, we leave the outcome to Ishvara, whether it is favourable or not.
 
When we do this, our mind and intellect do not constantly get destabilized by life’s ups and downs, leaving them free to contemplate the higher goal of Ishvara. But this can only happen through the practice of single-pointed worship, “ananya yoga”, the yoga where there is no other goal but Ishvara. In this manner, when we constantly worship Ishvara through our body, mind and intellect, he takes care of us. How does he do that? Shri Krishna completes this thought in the next shloka.