He is telling god that he knows he hasn't been the best at what he could be. He has forgotten and ignored God and he knows what he has done. Hes begging for forgiveness and hes sorry for what he has done. He knows he hasn't payed attention and that he has ignored Him. He's been searching in the wrong places for satisfaction. He wants to desperately keep what he thinks is satisfactory to him. Something earthly even though he knows that it won't do. It won't do at all. He's addicted to earthly satisfaction. Even though he knows it won't help, it satisfies him but only for a little while, for the earth is temporary. Hes begging, "screaming" for help, for forgiveness. He's sorry that he has rejected God's help, that he has forsaken Him. He hopes that God won't reject him after all he has done to Him.