In order to practise true yoga, the yogi needs to overcome the force of ego and unite with the true purpose of his life.
The ego is not a Freudian idea here; it simply means the role we play in our daily lives. It is the force which defines us as individuals by making us separate from others. In terms of the ego, we could define ourselves as a doctor, a teacher, a mother and the like. But these are temporary realities which can change suddenly and unexpectedly. When these realities change, we experience loss and confusion because our identity has been questioned.
The yogi strives to overcome the instincts that come from ego, such as conceit, greed, selfishness. The yogi does not have to become a hermit to avoid the force of the role she plays; she still has her active role in society, but she tries to remain mentally detached from this role, through constant meditation to remind her of her true identity as an eternal spirit.
Apart from meditation, service is a wonderful way to free one’s self from ego. Service means doing work which benefits others, without expecting anything in return. Service leads to divine blessings and good karma, because all your work is performed as sacrifice.
Another way to think about the ego is the idea of little self. We are so caught up with the little things that belong to us and support our identity that we forget how great we can be. If we expand our visions and possessions from just one house, one family, one job, from all these small things, then instead we could say that the whole world belongs to us. Then our life becomes service, it becomes a blessing for the whole world. Make yourself so selfish that you think of everything as your own: be generous with your selfishness and you will never lose anything.