"Do not say 'I am a youth,' for you shall go to all to whom I send you, and whatever I command you, you shall speak. Do not be afraid of their faces, for I am with you to deliver you," says the Lord. - Jeremiah 1:7-8
Here God is talking to Jeremiah and telling Him that He has given him a special mission and purpose. God is calling him, and Jeremiah tells God that he is just a child. Jeremiah thought he was too young, too inexperienced, not qualified enough to speak to people older and people "smarter" than him. But here God says "Don't let your age stop you from following me with your whole heart and life! If you follow me I will give you the words to speak, the strategy to use, where to go, what to do, and help you every step of the way."
The next thing that God says is "Jeremiah do not be afraid of people, do not be afraid of people older than you, people with more degrees than you, more power than you, and more money than you.... Anyone and everyone I send to you, I will give you confidence and authority over them. So don't be afraid! Even if they try to hurt you, kill you, or cause you to be defeated and humiliated, I will defend you, help you, and deliver you!" God is faithful to save us in our trouble, and He will always help us when we do what He tells us to do.
Don't let your age, fear of what others think, or fear of failure and opposition stop you from living your life fully for God. Don't let excuses stop you from being who God made you to be. If you do what God tells to do, He will honour and help you to the very end.