Your past does not even limit how God will use you in His Work. That dumb thing you did long ago will not keep God from using you in His Will if you are called to it. That hurtful thing you did does not exclude you from God’s Love and Kindness. That deep, dark, horrible sin you committed is not bigger than God’s Love and Kindness and Faithfulness. If God promised it it’s as good as done because all His Promises are yes and amen. You are not saved by Grace because of anything you’ve done or haven’t done. Grace comes from the Sacrifice of His Only Son, His Beloved Jesus, who died so that you would be spared punishment for your sinful ways.