The ancients believed that a universal will, pneuma, was like a breath of life blown into each of us. Whether they literally believed it or not, it served as a powerful metaphor for how heroic societies viewed personal mortality.
In their view, the world was a battleground of ideas, and what was important was the continuing evolution of those ideas (this is different from a Hegelian, Marxist or "progressive" worldview, in that the ancients did not believe in nor desire Utopia) to make the society a stronger version of what it already was. The individual was like an actor who, receiving his part cast by lot, would act it out according to what her or she knew from upbringing, genetics and experience.
There was no concept of the individual soul in the way we see it today; rather, the soul was something that pervading every individual. Another way to phrase this: where we conceive of ourselves as the motivating force that perceives what we know of our world, to the ancients, the force of life was what did this perception, and because it knew the world from a relative perspective through the individual, it appeared to the individual that he or she was perceiving the world.
This enabled them to consider their lives well spent if something was achieved, because not only did the force that produced all life, of which their consciousness was just a slice of its attention span, continue living, but the meaning and significance of their actions did also, to the point that they viewed it as transcending time and place to be focused on the idea and the importance of the idea.