The individuated consciousness, the soul, has evolution on three different planes of existence:
The terrestrial, the astral and the causal.
First, evolution is on the terrestrial planes like the Earth.
There are many lifetimes for the individuated consciousness projecting as a human being.
These lifetimes are governed by Natural Law to ensure that the soul stays in the stream of evolution.
This is done through Karma.
There is Karma that the individuated consciousness comes into a particular lifetime with.
This Karma must be worked out in this particular lifetime.
The soul keeps coming back as a human being until it is finally freed from the bondage of terrestrial Karma.
This is accomplished with a Meditation Practice that transcends the relative field.
The experience of the Transcendent That is Divine Being, transforms the mind and the physiology of the individuated consciousness.
In time, the mind and physiology are established in Divine Being;
Established in the Self.
This is Enlightenment.
Now, no more future Karma will be created in that lifetime.
When that body is dropped at the end of that lifetime, there will be no more returning as a human being.
Now the Karma will be worked out on the astral planes;
Higher planes of existence that are experienced primarily through feelings.
On these astral planes, life is longer and much happier than on the terrestrial planes like the Earth.
On astral planes the evolution of the individuated consciousness is through feelings;
Primarily through the feeling of love.
Love expands and grows until it culminates in the love of and devotion to God in God Consciousness.
Now the astral lifetimes come to an end.
But there is still Karma for the individuated consciousness to work out.
Now it will be on causal planes of existence.
The causal planes are the blissful realms of ideas.
Here evolution is through thought alone.
Thoughts and ideas fulfill desires;
No more action is required.
The Karma on the causal planes comes to an end when the idea of Unity Consciousness is realized:
All this is Totality.
All this is Brahman.
Brahmi Chetana, or Unity Consciousness is the Consciousness that finally liberates the soul from the bondage of Karma on all the different planes.
Now the individuated consciousness merges with Brahman;
With the Lord of Lords Who presides over the Absolute and the relative fields;
Who holds the Fullness of both within.
This is the usual path of evolution for the individuated consciousness.
There are times, however, when in one particular lifetime on the Earth, Enlightenment is gained;
God Consciousness follows;
And finally, Brahmi Chetana is realized.
There are souls who have the privilege of gaining the Highest States of Consciousness in one lifetime here on the Earth.
Why not be that soul?
Why not indeed.

Many thanks to Yogananda and to his Guru Sri Yukteswar as well as to my beloved Guru Maharishi.