Gita : Ch-2. Slo-48.

Srimad Bhagavad-Gita :

Chapter-2. ( Samkya-yogam )

Slokam-48. ( Krishna tells Arjuna that he should act in yoga  )

Yogasthah      kuru     karmmaani     samgam     tyaktva     dhananjaya,

siddhyasiddhyoh       samo     bhutva      samatvam       yoga     ucyate.

dhananjaya!  =   hey      Arjuna!

yogasthah  samgam  tyaktva   =   steadfast  in    yogam   and   having   abandoned    attachment;

siddhyasiddhyoh  samah  bhutva   =  keeping  the  balanced   (  equal   )  pose  ( mind  )   in  success   and   failure;
karmmaani  kuru  =   do   your  karmam  (work );

samatvam  yoga  ucyate  =  evenness of mind   (   Balanced    mind   )   is called   yogam.

The previous slokam-47 is further clarified here. Yogam, equanimity is the methodology encouraged. Relinquishing desire and attachment to the rewards of actions while steadfastly remaining equipoised in either success or failure. This verily is what is meant by equanimity. ( Yogam )

The meaning of the word sangam is attachment. Attachment to what? The rewards of one's fruitive actions.

Be steadfast in yogam, O Arjuna. Perform your duty and abandon all attachment to success or failure. Such evenness of mind is called yoga.

What should one do? Lord Krishna states here to remain balanced and equipoise. Discard the mentality of being attached. Be balanced in either victory or defeat and perform your duties. Karmmanni refers to duties the plural usage of duties indicates various obligatory and occasional duties; but the optional duty is not to be included among these as they are not required. Otherwise there would be contradiction between the former and the latter statements. Yoga is explained by Lord Krishna Himself as being in the state of equanimity.

The fundamental question which might be raised is what then is factually to be done? This is now being answered in this verse. Established in the science of yoga perform all activities. Yoga is the science of the individual consciousness attaining communion with the Ultimate Consciousness. Being established by this yoga perform actions relinquishing attachment, motivation for rewards and depend solely upon the mercy of the Supreme Lord in all one's activities. Totally unconcerned about success or failure, attainment or non-attainment resultant surrender in righteousness all actions as an offering unto the Supreme Lord. This is the eternal path called yoga by the wise as it consists of fixed concentration of the mind.

Krishna tells Arjuna that he should act in yogam. And what is that yogam?  Yogam means to concentrate the mind upon the Supreme by controlling the ever-disturbing senses. And who is the Supreme? The Supreme is the Lord. And because He Himself is telling Arjuna to fight, Arjuna has nothing to do with the results of the fight. Gain or victory are Krishna's concern; Arjuna is simply advised to act according to the dictation of Krishna. The following of Krishna's dictation is real yogam, and this is practiced in the process called Krishna consciousness ( balancing  evenness  of  mind  ). By Krishna consciousness only can one give up the sense of proprietorship. One has to become the servant of Krishna, or the servant of the servant of Krishna. That is the right way to discharge duty in Krishna consciousness, which alone can help one to act in yoga.

Arjuna is a kshatriya, and as such he is participating in the varnasramam-dharmam institution. It is said in the Viishnu Puranam that in the varnasramam-dharmam, the whole aim is to satisfy Vishnu. No one should satisfy himself, as is the rule in the material world, but one should satisfy Krishna. So, unless one satisfies Krishna, one cannot correctly observe the principles of varnasramam-dharmam. Indirectly, Arjuna was advised to act as Kriashna told him.

To be continued  ....