Bhagavad Gita Verse 38, Chapter 2

sukhaduhkhe same kritvaa laabhaalaabhau jayaajayau |
tato yuddhaaya yujyasva naivam papamavapsyasi || 38 ||
 
Treat joy or sorrow, gain or loss, victory or defeat with equanimity, and then engage in war. By doing so, you will not incur sin.
 
sukhaduhkhe : joy or sorrow
same : equal
kritvaa : make
laabhaalaabhau : gain or loss
jayaajayau : victory or defeat
tataha : then
yuddhaya : in war
yujyasva : engage
evam : in this manner
paapam : sin
na avaapsyasi : will not incur
 
This is one of the most important shlokas in the second chapter, and perhaps in the entire Gita. In essence, Shri Krishna instructed Arjuna to maintain equanimity, an "even keel" attitude, not just in war, but in any circumstance in life.
 
Let us take stock of where we are. We had seen that Shri Krishna was covering 4 main topics: 1) Informing Arjuna that his logic and reasoning was incorrect 2) Explaining the correct logic and reasoning to Arjuna 3) Providing practical guidance to implement this correct logic and reasoning 4) Describing the attributes of the individual who follows this teaching. We are currently in the set of shlokas covering topic 2 - the correct reasoning and logic.
 
After the first sub-topic of the eternal essence concluded, we explored the second sub-topic of svadharma. Shri Krishna is now about to conclude this sub-topic by pointing us to the ultimate goal of our spiritual efforts.
 
Having reoriented ourselves with the scheme of the second chapter, lets now examine the current shloka. On first glance, the lesson in this shloka seems unapproachable and impossible to carry out, to some extent.
 
We encounter joy, sorrow, victory, defeat, gain and loss almost everyday, even several times a day. And each time we encounter any of these situations, we get emotionally and sometimes even physically affected by them. At work, a meeting with your boss does not go well. But on another day, your boss gives you an exemplary speech on a project well executed. How can we possible treat these as equal?
 
Shri Krishna fully understands this point. Here, he only lays out the ultimate goal for us: the goal of equanimity, or treating each and every life situation equally without getting agitated. Now that we know what the goal is, he will gently guide us through a path of practical advice throughout the rest of the teaching in the Gita.
 
So as we read the rest of the second chapter, if we think we have lost sight of the goal, let's remember this shloka.