~ Choose LIFE, that you may LIVE! ~
is from Deuteronomy Chapter 30. 
Deu-teronomy is the 2nd "announcement" of the laws God gave to Moses,
which Joshua asked all the Israelites to read to each others before they enter the Promised Land.

Below is a post by  
Walk Thru the Bible <www.WalkThru.org>
 
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Deuteronomy 30

The covenant with the children of Israel is renewed.

INSIGHT

After laying out the options before the Israelites at Mount Ebal and Mount Gerazim,
God now says, "Choose."
But by His grace, He makes clear the consequences of these choices.

How terrible are the curses-and how wonderful are the blessings.
Seeing the alternative so clearly before us, what could possibly account for our choosing the curses?
The only conceivable answer is that we don't believe God.
We don't really believe that the blessings will be that good-or that the curses will be that bad.
The Old Testament was written for our instruction. We must learn to take God at His Word.
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Deuteronomy 30:19 and 20 in NASB on Biblegateway.com

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It's also a phrase in a Big Tent Revival song I hum sometimes.

from YouTube - During a Harvest Crusade in Southern CA
Choose life, that you might live
The life that He gives, He gives you forever.
Choose life, the way that is true
From the One who chose you,
You're the Father in Heaven
Choose life!
Continue lyric @
http://www.lyrics007.com/Big Tent Revival Lyrics/Choose Life Lyrics.html