Each person deems significant in life what derives, fundamentally, from the soul qualities that form one's essential self. This does not mean that significance corresponds to the pure motives of the soul. Rather, that no matter what the outer shape or form of one's life, every person, however misguidedly, is pursuing an ideal.
Such an ideal, of course, is not necessarily known to the embodied self. The embodied self, indeed, may not recognize having a soul-purpose at all, and yet one's tastes, preferences, and the things one takes delight in correspond, on a vibrational level, to something that at its root is positive and related to one's Divine self.
When an ideal in its pure form seems unattainable, it often happens that the embodied self will choose other substitutes, some faithful reflections of the original ideal, some poor, distorted, or corrupt reflections of the original. These distorted versions can be very far away from the original purity.
Nevertheless, every person is seeking their ideal self in manifestation all of the time. This is another way of saying that each person is seeking wholeness and completion. The ideal self, in its pure form, represents that state which is at one at the same time the Divine Presence within, and a portion of the Godhead in its qualities.
Even when one has abandoned the path of seeking goodness and truth in a conscious way, even when one has turned away from the light and become hopeless, cynical, disbelieving, or angry, there still is often underneath the wish that trust were possible and that love and truth were attainable. Disappointed idealists live all around us and their quest to be disabused of their cynicism is a poignant one.
What gives life significance?
Some would say the things we do that make us happy.
Some would say the people we love that love us in return.
Some would say the work we do that is of benefit to others.
Some would say the fact that we are alive.
To meditate on significance is to open the heart to what it holds to be most true. To realize significance is to live a life in keeping with that truth.