About as down to earth–and the pure truth–as you can get.
The Practice of the Presence of God is a short book (of 4 conversations and 15 letters) by Brother Lawrence, born Nicolas Herman), a 17th-century Carmelite friar, compiled by Father Joseph de Beaufort. More details here.
Available online (PDF, Kindle, etc.) here.
Available as audio reading (two forms) here.