The change occurs through conscious effort, through increasing awareness. it is something you can do on your own through enough will and reflection OR it can be achieved by someone of a higher consciousness pushing your energy beyond its current boundaries. Eric talks a bit about this in Reverse Engineering the Self. Basically they build up your frequency using thier own energy.
Think of the old saying, "You become like those you spend your time with".
In a manner of speaking it comes from outside you because its your higher self, that which is closer to god. But in a nother way of seeing it, everything is connected so it really comes from within.
To say it comes from outside of you would be true when speaking of your awareness/consciousness. It is outside the norm of your current reality. This would be a spiritual experience that expands your world view and shows you other possibilties. This is not to say it "must" happen this way, but more often than not it tends to require it because people are so deeply asleep.
In my own case I have never had any mystical experiences that caused me to start looking for answers. I have always had an innate desire to find it and it did not require a catalyst experience. I always wanted one but never found it. So this tells me that an outside force is not required (speaking of mystical experiences) to get you on the path. Once on the path you are really talking terms of development. The more profound experiences tend to be "leaps" forward as opposed to incremental changes in being.
I think it takes interest, sincere effort and consistence. I think it takes an open mind as well.
Does that make more sense?
So the short answer would be, no it doesn't require outside intervention but because of being asleep, most will find this to be their experience.
