Feeling Worthless
First, your feelings, while important, need to be properly informed by God's truth - the Bible, God's Blue Book - of our worth. Christians are children of the King of Kings. They are heirs of the righteousness of faith. They have been given all things that pertain to life and godliness. They have been judged righteous before Almighty God. Their salvation is sure. Their eternity is known. They shall live with Christ forever. So, who we belong to and who we have become needs to inform our feelings about our worth! 1 Peter 2:9-10 says:
But you are a chosen people, a royal priesthood, a holy nation, a people belonging to God, that you may declare the praises of him who called you out of darkness into his wonderful light. Once you were not a people, but now you are the people of God; once you had not received mercy, but now you have received mercy.
Second, we do not always feel like who we really are because we are not everything we can be, and although we are holy, we do not always act like who we really are. Again, as Peter says, "Be holy, because I am holy" (1 Pet. 1:13-17). We need to have a holy fear of God (1 Pet. 1:17) and put off our former lusts (1 Pet. 1:14). Your feelings of worth are closely akin to how we live and how we understand God's forgiveness. Though we are far greater sinners than we ever thought, we are also far more forgiven than we can imagine!
Third, in the natural world if we do not eat right, we can get weak and depressed. If we fail to eat right spiritually we get weak and feel estranged from God. When we eat properly, we understand our worth more fully. We need steady spiritual nutrition with the Word, prayer, fellowship, the sacraments.
Before you trade in a car, you attempt to make it look as good as possible to get the highest Blue Book rating possible. You wash and wax your vehicle. You vacuum the interior and clean the rest of the vehicle appropriately. The good news of the gospel is that while you do your very best to wash, wax, and appropriately clean yourself, Jesus takes out all the scratches, dings and marks, and you get the highest rating, as if you were still perfectly new and perfect. That's because in Christ you are new and perfect! Believe it, accept it, live it!

Dr. Joseph R. Nally, Jr., D.D., M.Div. is the Theological Editor at Third Millennium Ministries (Thirdmill).