It's a common human experience to feel incomplete. We may not realise it, but the search for fun, for love, for happiness, for excitement, for spiritual enlightenment, comes from the sense of being incomplete. In some ways it's a natural sense of feeling incomplete. If ever a being considers itself to be limited, then it feels it is less than the whole. And that's not right. Something will seem to be missing.
It's this wholeness that people seek. Wholeness is the true natural state. But human development at this stage of evolution causes it to feel limited, separate, lacking, wanting, and needing. From the physical perspective the interaction with the environment is necessary: humans need to breathe in air, drink liquids, eat solid food, and also do the opposite - expel solids, liquids and gases. That is part of human nature, of being a flowing quality of the planet. That in itself is fine. But human intelligence has developed further than other animals. Human intelligence has developed to become self aware. But this self awareness isn't accurate. Human self awareness concludes, "I am this body." But really the body isn't limited in this way - it is a flowing quality of the planet. The body isn't really limited and separate from the planet.
So here we have the development of human intelligence concluding that it is a limited being and there are other beings with limits. This limited human is inevitably incomplete. It will never be satisfied, trying to hold onto things, trying to seek happiness, looking for love and excitement, or spiritual enlightenment. The limited human being will not be satisfied, because the limited being is not an accurate identification. The world is unlimited, appearing as if there are limits. It is this appearance of the world that has fooled humanity. But it's all part of developing awareness.
There is no limited human. There is only the infinite What Is, Pure Consciousness. Its nature is as a singularity, without beginnings or ends, without want or need, complete, content, perfect peace.
The development of human awareness is an expression and blossoming of Consciousness in the world. It's not that the human being develops a higher awareness or consciousness level. It is rather that the errors and mistaken views of the human mind are lessened, revealing more and more the Pure Consciousness that is the true infinite nature of being.
How do we bring about this feeling of being complete? Really it's about letting go of the feeling of being incomplete, letting go of the sense of being limited. The recognition needs to dawn that I am not a limited being and I am not this body. Then should come a 'practising' of just being Awareness, without form, without attachment to this or that, acceptance without controlling, just simply being. This resting in the pure nature of just Being dissolves the sense of being a limited separate self, and the true nature of complete contentment comes through into the human experience.
This is usually a gradual process. It's called Enlightenment or Self-Realisation. It's simply the letting go of the erroneous belief of separation and limitation, and being as you are.