If anyone knew about growing as a Christian it was Peter. He wins the award for mistakes in his Christian walk, and yet, he grew. He was loud, brash, and overly confident. He denied the Lord at the time when the Lord needed him the most. He slept while his Lord wept. He ran away from the cross. And yet, he grew. He grew closer to Jesus with each passing year.
If you are having trouble growing as a Christian, listen to Peter. He knows.