Bhagavad Gita Verse 31, Chapter 2

svadharmamapi chaavekshya na vikampitumarhasi |
dharmyaaddhi yuddhaacchreyonyatkshatriyasya na vidyate || 31 ||
 
Furthermore, you should not be disturbed when you consider your duty, because there is no other glory for a warrior that a righteous war.
 
svadharmam : your duty
api : furthermore
cha : and
avekshya : consider
na : not
vikampitum : disturbed
arhasi : should
dharmyaat : righteous
hi : because
yuddhaat : than war
shreyaha : glory
anyat : any other
kshatriyasya : for a warrior
na vidyate : there is not
 
Shri Krishna now begins a fresh topic in these next few shlokas. He deals with the issue of svadharma, or one's own duty. It is important to remember that although Shri Krishna has addressed these shlokas to a mighty warrior, each of us has to interpret what they mean for us.
 
So, what exactly is one's duty? In this context, it is not something we have to do because someone else is forcing us, or because the so-called caste system says so.
 
Duty is work that one enjoys doing, has the aptitude and training for doing, and is not illegal or unethical. The practice of medicine becomes a svadharma for a doctor when he or she finds joy in the work, has completed medical training, and uses it for the betterment of society. Education becomes svadharma for students when they find joy in attending classes and studying for exams.
 
Note that the same person could have more than one svadharma. For example, a woman could be a mother at home, and executive at work.
 
One may ask, "I have the training and aptitude for my profession. I certainly do not perform any  illegal activities. But I don't find joy in my work. It is a drudgery for me, I only do it so that I can earn a living. How do I find joy in my work?". Shri Krishna has anticipated this question and will give us the trick for addressing this question very soon.
 
Let's also understand why Shri Krishna chose to introduce the topic of svadharma right after concluding the topic of the eternal essence. As we saw earlier, most of us are not at the advanced stage of spirituality where we have the ability to perceive the eternal essence in all beings, even though we may have an abstract or theoretical understanding of it by now. We are people with professions, jobs, careers and responsibilities. We are not in a position to retire to a monastery. Most of our day is spent in work.
 
Knowing this, Shri Krishna is gently introducing us to a more practical method of accessing the eternal essence. In this method, we can continue to lead our daily lives and still orient ourselves to accessing that eternal essence. As a side effect of this, we will also find joy and fulfillment in our work.