So this is really a core theme of the Bhagavad-gita. That in our words, thoughts, and especially in our actions we should be content with our intent and doing the best we can. From a spiritual prospective that is the success. If we are really doing the right thing in the right way, that is going to nourish ourselves and help others with the right purpose. That within itself is our success. The results we have no control over, but we do have control over the choices we make and the intentions that we have.
So yoga really means to make choices and to cultivate intentions and purposes that are wholesome and healthy for our well being, for the well being of the environment and for the well being of other people. And we should be grateful just for that opportunity. Just the action itself, just the motive itself is our success whatever the results may be. In that way our joy and fulfillment is transcendental to the apparent actions and reactions of this world.
In the Bhagavad-gita Arjuna was taught whether you win or lose is not important. Honor – dishonor, happiness – distress, success – failure, health – disease, life – death, all of these dualities are always playing with each other in this world, and we have some degree of control over the situation but not much. Yoga is not what the result is but your motivation in doing it and how you do it. If we are happy with that then our happiness is something very deep and circumstances and people in this world cannot meddle with it. – Radhanath Swami