Just in the same way Hell and Heaven are not places, but levels of consciousness.
The 3rd dimension is the physical world we all inhabit for a reason.
That reason is to learn how to control thought and emotion and to develop faith.
When you have a Thought, it immediately is pulled from the 5th dimension(where all possibilities exist at once) into the 4th dimension.
The 4th dimension is the Thought/Astral Realm. It's where your consciousness travels when you're sleep.
In the 4th dimension thoughts materialize instantly because that dimension vibrates at a higher and faster frequency.
This means that objects appear lighter and less solid than the dense/heavy objects appear in the 3rd dimension.
Everything first exist as a thought in the 4th dimension then as a physical manifestation of that thought on the 3rd dimension.
The reason we are here is because the 3rd dimension is the greatest school for the soul to learn how to control it's thoughts and emotions.
Remember in the 4th dimension thoughts manifest instantly so if you thought about a monster for 1 second, it would instantly appear.
This is why mastery is needed on the 3rd dimension before you ascend to the 4th.
There's a lag between thought and manifestation on the 3rd dimension. This time lag allows you to change your thought and emotional patterns way before they materialize.
One minute you can be thinking about suicide, which would manifest instantly on the 4th dimension, and the next you could be thinking about how lovely life is the next.
If you existed only in the 4th dimension, you would be dead already because there would be no time to change your thought and emotion before they manifest.
In order to manifest something in this 3rd dimensional matrix, you must give the thought constant attention and energy.
Once the thought has enough energy, it will become dense enough to manifest into the dense 3rd dimensional world.
That's the basis of the law of attraction.
It's knowing that you are a MULTI-DIMENSIONAL BEING.
You Feel Happy and Great before the physical manifestation because you know it's already manifested in the higher dimensions. You're just feeding it energy consistently so it can materialize in the 3rd dimension.
This is why the Egyptians said "Know Thyself".
Because if you truly knew what and who you we're, you wouldn't ever think and feel a negative thought or emotion again because you knew it would manifest sooner or later.
Imagine right now that you have ALL that you desire.
How does that FEEL?
Now that is your TRUE REALITY , if you FEEL that way long enough it WILL MANIFEST because the FEELING will produce the thoughts needed to manifest all your desires automatically.
Don't let your bank account, your peers, or anything in your current reality convince you that this is not your TRUE REALITY anymore.
What you are currently viewing is your OLD REALITY that was based off your past FEELINGS.
But you've just created a NEW TRUE REALITY, that will manifest if you hold the FEELING long enough for the Thoughts to Materialize in the 3rd Dimension.
Whenever your thoughts try to tell you that you don't have all you desire already, immediately cancel that thought and replace it with a affirming thought.
Stop letting your mind recreate your old reality over and over again and take control so your NEW REALITY can manifest.
This is where you learn true FAITH. Believing and FEELING something you can't quite see yet but deep down inside you just KNOW it's manifesting.
Until you learn these lessons of thought/emotional control and FAITH, you will continue to re-incarnate in this 3rd dimension until you learn it.
Then and only then, are you ready to ascend to the next school.