The karma which helps you unite with God, has been declared to be “Karma Yoga” by Srimad Bhagavad Gita. This Karma Yoga is the source not only of peace and well-being, devotion and liberation but also of perfection in any work or duty.
Karmanyevadhikarste ma phalesu kadachana –
(Sri Sri Gita 47/2)
You have always every right to carry on your own work or duty but absolutely no right to the fruits of your karma (leave that to the Supreme).
“Yogah karmasu kaushalam”
(Sri Sri Gita 50/2)
— This skill in karma (action) the practice of this tactic in every step of your work is Yoga according to the Gita. But if you perform any tasks thinking that you are doing it for your children, friends and relatives, society or the country, some ego or stress is bound to be produced in you. Then the karma will turn into the ordinary grade, the kind that will engender bondage, worry and evil dispositions.
Karma is mandatory for all and it will have to be performed, but if you do it to please, to worship God, your worldly attachment will decrease, your mind will be calm and peaceful and your work will also be done better. Now, even if there are any difficulties, they will cause no anguish because you are working only to please God and to win His love. Your mind will no longer be anxious about success or failure and this will make your mind peaceful all the time.

Sri Ramakrishna explains this with a beautiful illustration: —In fairs one may see some dancers are dancing with great finesses, balancing pitchers on their heads intact. One has to remain active in the multifarious activities of life in the same manner, but the pitcher on the head must be kept still, that is to say the mind has to remain steadfast in God. The Scriptures also provide the same simile –”maulistha kumbha parirakshanadhi nativa” – Just like the dancer whose mind is always vigilant on the pitcher overhead.

Let us clarify distinctly the fundamental differences between common karma or Sakam Karma (Karma with desire or expectation) and Karma Yoga or Niskam Karma (or Karma without desire or ambition) which links us to the God-Head.

In ‘Sakam Karma’ we cannot rightly concentrate so deeply on our work or duty as our minds normally get distracted or disturbed with the imaginary rosy pictures of the good fruits of our Karma. Secondly, if our dreams are fulfilled we are so much elated, restless, sometimes proud also as to neglect our duties then or later on. Thirdly, if our dreams are not fulfilled, more often than not we become a helpless prey to frustration, depression and all that.

On the other hand if we adhere to ‘Karma Yoga’ e.g., if we go on doing our work or duties, (whatever that may be) indifferent to whatever fruits (good or bad) they bring forth – our minds always remain peaceful and our concentrations undivided.

Again, if we are able to perform our work as worship to God, only for his pleasure and with no other end, our minds consequently reach a sublime state. And, as a result of both these approaches, we are bound to do our work with much more efficiency and elegance undoubtedly.

Secondly, in case our desires, rather hidden desires, are fulfilled through this Niskam Karma Yoga we do not get so much elated, egotistical or proud because we have been trained to take all these good fruits of our Karma as His kind blessings or Prasadam (Oblation) not as the offshoots of our Karma done.

Thirdly, in case our suppressed desires are not fulfilled for any reason whatsoever we shall never be a victim to depression frustration or tension because we have already been tension-proof by offering the fruits of our Karma at the lotus feet of the divinity.

Thus through the practice of Karma Yoga we can very well avoid the minus points of Sakam Karma (attachment, depression, anger, ego, etc.) and get so much profited with the plus points of Niskam Karma (e.g. efficiency, self-contentment, mental peace, and divine bliss.)

Sometimes one feels that all these are mere theories. Is it really possible to be free from attachment and fix the mind steadfastly on God? If there’s no attachment to work, if there’s no expectation of fruit, then how will one feel inspired to do the work?
One of the greatest Yogis and Karma Yogis of the world Swami Vivekananda has answered this question:

“Even I used to feel like that before, but as I got enlightened gradually, I realized that’s not true. The lesser are we attached to the work the better can we work at it. The more peaceful we are, the more work we will be able to do. If you read the lives of most accomplished men of the world who have done great work, you will find them to be men of extraordinary calm. Nobody could destroy the balance of their mind. Every page of the Gita bears testimony to it –an intense skill in action; but even in it a perennially pacific attitude. This is state, which has been declared as ‘Karmarahasya.’ The aim of Vedanta is to attain to that state.”
(Karmajivane Vedanta – 1: Jnana Yoga)