Fretting makes you become peevish, irritable and impatient; God does not want you to live that way. He wants you to live the abundant spiritual life that Jesus died on the cross to give you. You must not let the precious price that Jesus paid for you to go to waste!
The Word of God tells us in Psalm 37:1-4
, "Do not fret because of evil men or be envious of those who do wrong; for like the grass they will soon wither, like green plants they will soon die away. Trust in the Lord and do good; dwell in the land and enjoy safe pasture. Delight yourself in the Lord and He will give you the desires of your heart."