Here are a couple quotes from the Brother Lawerance book Practice of the Presence of God. 

“If you are young, my brother or sister, learn - I beg you - from my confession, that I cared too little to employ my early years for God.

Consecrate all yours to His Love.

If I had only known Him sooner, if I had only had some one to tell me then what I am telling you, I would not have delayed so long in loving him. Believe me, count as lost each day you have not used in loving God.”

He continues,

"The presence of God is thus the life and nourishment of the soul.”

—From Practice of the Presence of God by Brother Lawrence

Here are a  couple links to this book;

Here is a link to the version of this book that I have read.

Here is a link to a version written in more modern / readable english.