What is the importance of concentration?

The Persian poet wrote—

There is no Heaven or Hell but that which man creates for himself. 

He might have added with equal truth that you create yourself, and build yourself around the life, which is yours. You do it by your thought, just as you create your conditions by your thought. So again, let me impress upon you the importance of concentration; according to your thought are you created, for you are recreated, reincarnated daily. You change every hour, and the change is the result of the thought. So think thoughts of life, thoughts of reality, thoughts of vital love, and attract that understanding, which is life everlasting.

—Spirit Ione