To build yourself up in faith means that you have to do something to increase your faith. See if this helps:
I know that Jesus died and rose from the dead — for me.
I know that I have asked Jesus into my heart to be my Lord and Savior.
I know my sins are forgiven and I am clean.
I know that I am filled with the Holy Spirit.
I know I belong to God.
I know He loves me passionately.
I know I am rooted and grounded in His love.
I know God has a destiny for me that I will love.
I know that I have peace because I have all the gifts of the Holy Spirit.
I know all of heaven is open to me.
I know I’ve been given all wisdom.
I know I have all authority to speak in Jesus’s name.
I know the devil must leave me when I rebuke him.
I know that I can pray for the sick and they will get better.
I know I can pray for miracles to happen, because God loves me.
I know I can ask for more from God and He will give it, because He wants to bless me.
I know that God wants to bless me.
I know that He is a good Father.
I know that nothing is impossible with God.