Perform action, O Dhananjaya, being steadfast in yoga, abandoning attachment and being balanced in success and failure! Evenness of mind is called yoga.
(Bhagavad Gita 2:48)
People are generally elated by success and depressed by failure. Elation and depression are attributes of the mind. If one wants to become a real karma yogi, one will have to keep a balanced mind at all times, in all conditions and under all circumstances. This is no doubt difficult, but one will have to discipline the mind through constant practice in order to have peace of mind and real, lasting happiness. The person who keeps a balanced mind is a jnani, and karma yoga prepares the mind for the attainment of jnana. That is the beauty, secret and essence of karma yoga.
Many people are attached to their work. They like a certain kind of work and take interest in it, but dislike some other type of work. They are unwilling to leave the work they like, even if conditions require it. They take undue responsibility on their shoulders, pine and labour under worries and anxieties. However, this is not yoga at all because there is attachment to the work due to the quality of rajas.
There must be no attachment to any kind of work. One must be ready to discontinue any work at any time. There may be a divine call for certain work and one will have to take it up at once without any grumbling, whatever may be the nature of the work, whether one is willing or not.
If there is a divine call, one may start a worldwide movement or stop the undertaking, if conditions and circumstances demand it. One should not care whether there is success or failure, but simply obey the divine call and act like a soldier on the battlefield without any attachment to the work. There is great joy in karma yoga because there is no personal element present.
Keep the reason rooted in the Self. Have a poised mind amidst the changes of the world. Work for the fulfilment of divine purposes and do not expect any fruit. Do everything as an offering to and worship of the Lord. Work for the welfare of the world in accord with the divine will and allow the divine energy to work unhampered through your instruments. The moment your egoism enters, there will be an immediate impediment to the free flow of the divine energy.
Make your senses perfect instruments for His lila. Keep the body-flute hollow by emptying yourself of egoism, and Krishna, the flute-bearer of Vrindavan, will be able to play freely through you. As He will work through your instruments, you will feel the lightness of the work. You will feel that God works through you and that you are quite a changed being. You will be freed of your responsibilities and live as free as a bird. However, your egoism will try to re-enter, so be careful and on the alert.
By gradual practice and purification of the mind, you will become an expert in karma yoga. Your actions will be done perfectly and selflessly and culminate in jnana or spiritual wisdom. This is the goal of karma yoga and the yoga of equanimity.