Chapter 2, Verse 18
antavanta ime dehā
nityasy-oktāḥ śarīriṇaḥ
anāśino’prameyasya
tasmāt yuddhyasva bhārata
Finite bodies have an end, but that which possesses and uses the body is infinite, illimitable, eternal, indestructible. Therefore, fight, O Bharata (Arjuna).
“Finite bodies have an end,” Krishna says, “All bodies, which have been created from matter, from the five elements, ‘have an end’.” Everything which is matter, will return to matter. Here the Lord is saying that the mind, the senses, and the physical body are all perishable. Whatever you see outside is perishable, has its limit and will have its end. But you are here to use these limitations to do your duty, to do your dharma. This infinite, the Atma, which is present inside of you is the Reality. He says, “Don’t be in ignorance. Know that you are eternal. Know that you are indestructible. So fight!”
Here Krishna is not only talking to Arjuna, He is talking to everybody, “Don’t go into your weakness, My dear children. It is Me who is seated within you. Look at life. Face it! Be strong! Know that I am with you. And know that we have this deep, eternal relationship together, that we are always next to each other. You are not alone because I, the Supreme Spirit, am ever-present with you.” Don’t look at the outside and become miserable! Don’t look at the effort that you are putting into your sadhana; just do it! Do your maximum! Don’t go into your weakness when you do your sadhana, but be in your power! Only then will you realise your Self. Only then will God reveal Himself to you. Don’t look at the outside world. Don’t listen to ‘x, y, z’. Go with your feeling. Open your heart and be powerful! Be strong! So Krishna says, “Arjuna, don’t show any hesitation or unwillingness to engage yourself in the fight.”
Bhagavad Gita