Chapter 3 Lesson 1

In the first Chapter we saw that Arjuna was deluded and dejected. He did not really want to fight the horrible war. Which could also mean that when man is deluded, depressed, attached to outcomes of actions, he loses desire to ‘act’
If you go back, Krishna had explained Arjuna the nature of the Aatman.
To recapitulate: The Aatman is imperishable unchanging and eternal.
Everyone and specially Arjuna in this case should aspire to that state.

So now Arjuna asks Krishna a relevant question, which may have even occurred to you:

“If the aim is to achieve liberation and recognize the Aatman” Arjuna asked: why should I (fight) engage in action?
Arjuna continued to ask Krishna: “Do explain to me, the one discipline by which I may obtain, the highest good?”
Krishna replies: Some pursue the path of knowledge and others pursue the path of action…however none can remain inactive, as everyone is driven to action…He excels who acts remaining unattached (to the fruits of the action)in a spirit of sacrifice (prayer).