Karmanyevadhikaraste

karmanyEvAdhikAraste mA phalEShu kadAchana
mA karmaphala heturbhooh mA te sangostvakarmaNi

Your right is only to work, and never to its fruits.
Don't be motivated by the fruits of work. Nor should you be attached to inaction.
This is perhaps the most famous verse (2.47) of the Bhagavad Gita. Many people have not read the Gita, but they are familiar with this shloka.

The shloka (and the philosophy of Karma Yoga) tells us to renounce the fruits, or results, of our actions. Exactly what are these "fruits"? In a narrow sense they could be tangible gains – like a salary hike or a promotion. In a broader sense they could be the achievement of one's life's ambitions – like wealth, fame or power. These are the things people usually mean when they talk about "fruits" or "results".

There is another, more fundamental, "fruit" of action that is seldom talked about in this context: the happiness, the satisfaction and the peace of mind that one gets from work. Does "fruits of action" include these as well? Is Krishna telling us that we should renounce these also?

Imagine doing a work and saying no even to the joy that we get from it. It is one thing to do good work letting go of money, power and fame. It is another thing to do it letting go of even the happiness that it gives us. Doesn't this sound heartless? Yes, it does. Some would argue that the satisfaction and peace of mind we get from good work are an intrinsic part of that work, and should not be seen as "fruits" of work. But if we really think about it, we realise that these are also "fruits" of work, and hence should be renounced.

Which brings us to perhaps the most fundamental, the most primordial, "fruit" of work – the sense of meaning and purpose that one derives from it. Are we to renounce this as well? Yes, that is what the Bhagavad Gita is telling us. This is Karma Yoga at its most severe level: working purely for the sake of work, and not for any other reason. The work itself is its own justification, and nothing else.

This looks more like a philosophy of meaninglessness and nihilism than like a philosophy of Truth and salvation. But that is how the Path is.
kshurasya dhArA nishitA duratyayA
durgam pathah tat kavayah vadanti

The razor's edge is difficult to walk on
Likewise the wise say the Path is hard.
(Katha Upanishad, 1.3.14)
To become a Yogi one has to look the cold truth in the face. As Dag Hammarskjold said: "Never let success hide its emptiness from you, achievement its nothingness, toil its desolation. Your duty, your reward, your destiny are here and now."