Labor: the ongoing exertion of effort required to keep a living organism effectively functioning. Can bring great joy ... and pain ... is not intrinsically oriented toward growth. Will be increasingly obsoleted as technology advances.
Work: the creation of works ... the exertion of effort to make new things (which may be material, conceptual, social-relational, etc.) ... oriented toward growth as well as joy
The mixture of work with labor characterizes the modern era, but the correlation of the two will decrease as technology advances.
Once work is separated from labor, what remains? Essentially, work as art-work and social communion ... the creation of scientific, mathematical, visual, engineering, architectural works, not to put food on the table, but to gain social relationships and most of all just for the feeling of doing it and the joy of getting it done.
Social action: the creation of works whose impact lies in the social realm ...
Hannah Arendt's excellent book The Human Condition gives a rather clear and erudite exposition of the above categories.
She also makes the bold assertion that only through social action are people able to truly express freedom, and able to truly be human.
If one interprets "being human" as "contributing substantially to the collective, emergent mind of human society" then she is correct.
Is Labor Necessary?
Work and social action seem critical for advancing Cosmist values ... labor less and less so as technology advances
Whether the human body needs some sort of labor to be joyful is another question -- but if it does, one may view this as a shortcoming of the human body-mind rather than as an indication of the fundamental cosmic importance of labor.
According to what we know of physics, some entity must "labor" in some sense in order for physical dynamics to happen ... for metabolism to occur, for structures to get fabricated, etc.
But technology has the capability to push more and more of the labor onto entities with less and less intense sentience, away from entities with rich theaters of deliberative awareness and high levels of intelligence.
As our minds, society and technology advance, work and social action should become increasingly disssociated with labor -- among humans and other intensely, deliberatively conscious beings we may create or evolve into.
If this doesn't happen, it will probably mean we are handling our technological transcension in some profoundly wrong way.
The Power ... and Limitations ... of Play
And what of work's sometime antonym, play?
Play: not just spontaneous joy-inducing activity ... much of play involves the pursuit of goals that are analogous to, but easier to achieve than, goals an intelligent system finds important. Via pursuing these analogous goals, the organism may learn something about how to achieve the real goals of interest. The joy of play comes from the intrinsic activity, but also from the analogical connection to important goals...
If you're forever playing, and only playing, then play loses much of its meaning, which comes from its analogy to real-life goals.
Children can fully enjoy a life of pure play, because evolution has crafted their psychology to be "that of folks who will become adults." But it's famous how fast pure play grows boring for most early retirees.
For grown-ups, alternating play and work/social-action, with rich analogies growing and changing and binding the two realms of activity, is probably the most fulfilling way to live.
One could engineer a mind to enjoy an endless life-story of pure play without any need for work or social action. No doubt some human minds have self-organized into such a condition, already. But Cosmism views this as suboptimal: pure play will never lead to powerful growth. And without growth, ultimately, the scope of joy is limited -- part of growth is the ability to experience more and more joy as one expands the scope of one's capabilities and experiences.
All work and no play makes Jack a dull boy; but so does all play and no work.