You are like a wave in the ocean of Existence. The wave rises up from the ocean but it is still connected to the ocean. It may think it has an individual existence but that is just a myth. Whether it is rising, above the ocean or falling down, it is still a part of the ocean.
On its own, because of joy, when the wave takes the body, there will be no gathered or agamya karma. When agamya karma is acquired, it will corrupt the total sanchita karma that was pure. This sanchita karma has to be exhausted in the next birth. Corrupted total sanchita karma generates the cycle of life and birth. This is how the wheel of karma starts.
The new body that the life energy occupies does not remember the prarabdha karma that the life energy brought to it when it took the body. So, you do not remember the desires with which you left your previous body.
Reminding yourself of those desires again and fulfilling them in this birth is what doing tapas or penance and becoming enlightened is all about.
So what happens when you forget at birth that you have come through divine play? When the total karma weight becomes excessive, you realize, ‘There is some problem somewhere.’ Immediately you wake up and get enlightened again. The rewinding and coming back is enlightenment.
Sometimes, if you get a really bad dream, only a thought like ‘I am dreaming’ will come at first. Then, you actually wake up. That thought of ‘I am dreaming’ coming is turning towards enlightenment. Waking up is getting enlightened.
That thought of ‘I am dreaming. This whole world is a dream.’ and then renouncing the false world and catching the reality is enlightenment. In this world, the same experiences repeat making you tired and bored. It gives rise to the suspicion, ‘I am seeing a dream.’ Then, you start doubting the world, doubting the promise the world gives.
It is like the newspaper ads about some beach side resort that will show the beach, the table, the food, all looking like heaven, giving a promise of luxury. You doubt that promise, because you realize that if hundred people see this and go, not many will actually feel the ecstasy promised. Similarly in life also, you doubt the promises your mind has been making all along but never fulfilling any.
source: Living Enlightenment