Bhagavad Gita

ಯೋಗಸ್ಥಃ ಕುರು ಕರ್ಮಾಣಿ ಸಂಗಂ ತ್ಯಕ್ತ್ವಾ ಧನಂಜಯ ।
ಸಿದ್ಧ್ಯಸಿದ್ಧ್ಯೋಃ ಸಮೋ ಭೂತ್ವಾ ಸಮತ್ವಂ ಯೋಗ ಉಚ್ಯತೇ ॥೪೮॥
yogasthaḥ kuru karmāṇi saṃgaṃ tyaktvā dhanaṃjaya |
siddhyasiddhyoḥ samo bhūtvā samatvaṃ yoga ucyate ||48||

Gist of the sloka:
O Dhannanjaya. Remaining in this yoga, perform your actions. Remove the attachment to the rewards, irrespective of your win or loss, be in steady state of mind. This is called yoga.
Lord Krishna instructs Arjuna that one should have single minded intention to do the duty which has fallen on one without worrying about the final rewards, which may or may not be favorable to oneself. Keeping one in a steady state of mind, irrespective of the result, one should always perform one’s duties to his fullest extent.
Yoga means a path to/solution/alignment with - Lord. If it’s not related to Lord then its not considered yoga. Lord Krishna here is instructing the art of Karma yoga to Arjuna.
Dhannanjaya means one who is an expert in the art of warfare and has many riches. He who has extended the boundaries of the kingdom and won many wars. The spiritual meaning means one who has access to the knowledge of the Lord – which is the real wealth. Being an avatar of Indira the celestial king, Arjuna was also the foremost gynani at that time on the Earth [apart from Bheemasena]. Hence the reason Lord Krishna called him Dhannanjaya.
If a person performs many sacrifices, without understanding the deeper meaning that the Lord within us, has given us this body, opportunity, materials, various arrangements to perform the sacrifice as a worship/service towards the Lord, then such a sacrifice is wasted effort. This is a sacrifice without awareness of Lord.
If he performs such a sacrifice with the knowledge of the Lord behind every event/action, then it becomes yoga [karma yoga]. This takes us nearer to Lord.