Swami Vivekananda took 8 lectures on Karma Yoga in Dec 1895, and Jan 1896, in Vedanta Society of New York (which was founded by him). His talks were titled

  1. Karma in its Effect on Character
  2. Each is great in his own place
  3. The Secret of Work
  4. What is Duty?
  5. We help ourselves, not the world
  6. Non-attachment is complete self-abnegation
  7. Freedom
  8. The Ideal of Karma-Yoga 

Below is my attempt of summarizing his talks in 25 Quotes (taken from his lectures), which can trigger you to enquire more & go deeper.
In a sense, here is the TL;DR version of his talks.

  1. The goal of mankind is knowledge, not pleasure.

  2. No knowledge comes from outside; it is all inside.

  3. We are responsible for what we are; and whatever we wish ourselves to be, we have the power to make ourselves. If what we are now has been the result of our own past actions, it certainly follows that whatever we wish to be in future can be produced by our present actions; so we have to know how to act.

  4. Love, truth and unselfishness, form our highest idea, because in them lies such manifestation of power.

  5. Our first duty is not to hate ourselves. He who has no faith in himself can never have faith in God.

  6. The householder should be devoted to God; the knowledge of God should be his goal of life. Yet he must work constantly, perform all his duties; he must give up the fruits of his actions to God.

  7. Each is great in his own place, but the duty of one is not the duty of other.

  8. Helping man spiritually is the highest help that can be given to him. Next to spiritual comes intellectual help.

  9. Each work is necessarily a mix of good and bad.

  10. Every work we do creates an impression on the mind, and even when such impressions are not obvious, they work subconsciously.

  11. Freedom of soul is goal of all Yogas.

  12. Work through Freedom! Work through love! 

  13. True love is unattached and selfless.

  14. Do not injure others is a universal duty.

  15. We are all debtors to the world and the world doesn’t owe us anything. In helping the world we really help ourselves.

  16. We ought not hate anyone. The world will always continue to be a mixture of good and evil.

  17. Non-attachment is complete self abnegation (denial of own self interest)

  18. The highest ideal is eternal and entire self-abnegation, where there is no “I” but all is “Thou”.

  19. Whether he is conscious or unconscious of it, Karma Yoga leads the man to that end.

  20. Work selflessly. Work unattached.

  21. Two ways of giving up attachment

    1. Bhakti  – Give up the fruits of work unto the lord. Surrender and say “Thy will be done.”

    2. Gnana + Those who done believe in God – Work with their own will, and with power of mind & discrimintation work – I must be non attached.

22. The sum total of the good things in the world has been the same throughout in its relation to man’s need and greed.

23. Karma Yoga is attaining through unselfish work, of that freedom which is the goal of all human nature.

24. We cannot add happiness to this world; similarly, we cannot add pain to it either. The sum total of the energies of pleasure and pain displayed on earth will be the same throughout.

25. To work you have the right, but not to the fruits thereof.

ps: Some of these are profound, and require deeper discussion. Please comment which one you liked the most, or if you would like more commentary or discussion on any of them

pps: Background – As part of teaching a Life & Works of Swami Vivekananda course, I have been going through his teachings in more depth and sharing it in summarized manner.