Bhagavad Gita

The dialogue between Arjuna and Krishna revolves around the dilemma of 'to war or not to war' against his kinship.  Krishna counsels Arjuna to perform his duties as a warrior (reflecting the importance of maintaining duties are per assigned roles within the caste system) over his duties over familial ties.

My interpretation of the Gita is that it is a story of how to cope with internal dilemmas, of managing passion and reason, of managing suffering (grief, anxiety, making difficult moral decisions, etc.).  Krishna argues that passion (in this context, Krishna's moral dilemma) is fleeting (33).  To overcome 'passion' through discipline is to achieve inner peace.

"Arjuna, you must learn to endure
fleeting things - they come and go!
When these cannot torment a man,
when suffering and joy are equal
for him and he has courage,
he is fit for immortality." (33)

Without attachment to desire or to fruits of action, one can attain inner peace/transcendence/enlightenment (immortality) (40-41) thus reducing/removing suffering (44-46).

I do not read 'immortality' literally, rather to me, it denotes inner peace.  Longing/desire/attachment causes self-inflicted suffering.  To let go of these attachments is to relieve suffering and also to understand that pain, suffering, happiness and all of life is ephemeral.

Krishna points to the illusion of self (individuality/ego) (47),  and notes the unity or connectedness of all life/nature/creatures (69).

"he sees the self in all creatures
and all creatures in the self.
[...]
I exist in all creatures,
so the disciplined man devoyed to me
grasps the oneness of life;
wherever he is, he is in me. (69)

When one lets go of the self/ego/individual, one affirms the ephemeral nature of life and gains greater respect for our surroundings and the other creatures around us.  I am not "me", rather I am also the water I drink, the air I breathe, the plants I eat, etc.  Everything is interconnected (which is how I read Krishna's statement of "I am in everything").  Krishna's teaching in this text is very Buddhist in its core.

There are various ways to achieve inner peace (e.g. meditation, yoga).

After class thoughts: I do not see reaching inner peace/nirvana so much as a desire, rather it speaks of a continuing process to attain this state of mind.  I do not think it is possible to be in nirvana 24/7.  We are human and we feel anger, pain, happiness, jealousy, etc.  To detach from the emotions that cause us psychic and in turn real physical pain (e.g. heartache), that is to attempt to reach nirvana through meditation, yoga, etc. is a coping mechanism to deal with those painful emotions.

Bhagavad Gita: Krishna's Counsel in Time of War
Translated by Barbara Stoler Miller (2004) Bantham Books.