Now, here is the mechanism. You are the boss of your mind. And you can order your mind what to think, when to think, how to think. Once you control your thoughts, you control your feelings because your feelings are created by your thoughts.

Isn't it great if you can control your feelings all the time? Isn't it great if you feel 'peace' all the time?

There are thoughts and feelings within us. Here is a question. Where do they come from? It seems they just happen to us and we don't know their origin. Most of the time, they are triggered by stimuli outside. And that's what's happening to most of us. However, external stimuli are not the origin of thoughts and feelings. They are just triggers. The origin exists somewhere else.

"We live in two worlds, inner world and outer world at the same time", said John Kehoe. In our inner world, there are thoughts and feelings. In our outer world, there are circumstances, environments, and conditions.

I read a book long time ago in which the author wrote the sentence, 'There is no world outside'. I don't remember the title nor the author's name of the book. But the sentence has been stuck with me since then up until now. 

Then finally, I feel I have deciphered the meaning of the sentence.