NRSV: Keep your heart with all vigilance, for from it flow the springs of life.
Good News Bible: Be careful how you think; your life is shaped by your thoughts.
NIV: Above all else, guard your heart, for it is the wellspring of life.
KJV: Keep thy heart with all diligence; for out of it are the issues of life.
New Living: Above all else, guard your heart, for it affects everything you do.