Writers 
A success roadblock closely related to fear is doubt. Doubt is a lack of assurance. When we doubt, we become unsteady, tentative, and wavering in our pursuit of a goal. We may not become paralyzed or be put into flight mode as with fear, but we may become bogged down and miss important opportunities for advancement.
Believing you can achieve a God given goal is vital to reaching a God given goal. The writer of Hebrews stated, “Without faith it is impossible to please Him, for he who comes to God must believe that He is, and that He is a rewarder of those who diligently seek Him” (11:6). How do you please God? You please Him by receiving His Son, Jesus Christ, as your Savior, and by obeying Him day by day. Part of your obeying God is doing what God tells you to do, not only in the commandments of the Bible, but in the pursuit of goals that God has designed for you. Without faith in God and without believing that God desires to reward you and will reward you as you diligently seek to follow Him you fail.
As with fears, you must face doubts head-on. You must ask, Why am I doubting? There are several reasons for doubt. One is a lack of understanding that God is with you always. Anytime you are concerned about whether God is with you, I encourage you to read aloud one of these passages of the Bible as often as you need to read it until you truly believe it:
• Philippians 4:13: “I can do all things through Christ who strengthens me.
• Philippians 4:19: “My God shall supply all your need according to His riches in glory by Christ Jesus.
• Hebrews 13:5: “I will never leave you nor forsake you.
• John 16:24: “Until now you have asked nothing in My name. Ask, and you will receive, that your joy may be full.”
• Matthew 7:7: “Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you. When I experience momentary doubt, I usually get on my knees, open my Bible, and read it aloud to God, saying, “Lord, this is what You have said in Your Word. I trust You to do this in my life. Doubt Caused by Past Failures. Another reason that people doubt is their past failures. They conclude that because they failed once in the past or perhaps even several times God is not with them and they are bound to fail again.
Most of us need to stop looking over our shoulders at our past mistakes.
To do so is to continue to carry guilt with us over sins that the Lord has already forgiven and forgotten. When we continue to bemoan past failures even though we have confessed those sins and failures to God, been forgiven for them, and made a decision with our wills to repent of them and change our ways we are stating that we have not been able to forgive ourselves. We are carrying excess and unnecessary baggage in our lives.
If God has forgiven you, which He says He does every time you confess your sins to Him, then forgive yourself! (See 1 John 1:9.)
The more you cling to past failures and cause them to produce doubt in your life, the more you destroy your confidence in the Lord. You begin to see yourself as a failure that God cannot use, a “mistake” that God has made, an unworthy person whom God cannot redeem or use for His purposes. That thinking is unscriptural. You have never made a mistake that God cannot forgive, remedy, and work toward your good eventually. You don’t have the ability to mess up so much that God will reject you or turn away from using you. You cannot undo the bonds of love that He has wrapped all around you. If you think you are a failure, you’ll act like a failure, and the things you attempt to do will fail. Choose to lay down your failure mentality, and see yourself as a beloved, talented, and spiritually gifted child of God. Act as the saved, Holy Spirit filled, on your way to being conformed to Christ person that you are. Don’t wait for others to do what you must do. Yet another reason that people doubt is that they expect others to provide opportunities and blessings to help them succeed. They wait for someone else to do the believing and to do the work necessary to accomplish a goal. When that someone else doesn’t show up, they begin to doubt.