Colossians 2:6 As you therefore have received Christ Jesus the Lord, so walk in Him, 7 rooted and built up in Him and established in the faith, as you have been taught, abounding in it with thanksgiving.

Apostle Paul says we should walk in Christ Jesus just as we have received Him. To understand how we received Him, we have to check the process of salvation. The second thing will be how we are supposed to grow in Him and be established. He said the process is the same thing as the process of our salvation. 

Romans 10:9 If you confess with your mouth the Lord Jesus and believe in your heart that God has raised Him from the dead, you will be saved. 10 For with the heart one believes unto righteousness, and with the mouth confession is made unto salvation.

So by confession of what Christ has done and believing the same, we received salvation. Then, to become steadfast and growing in Him we must also believe and confess. The growth we are talking about and the establishment of the saints is about their understanding. It is our knowledge and understanding of the same that determines our walk and establishment. 

2 Peter 3:18 Rather, you must grow in the grace and knowledge of our Lord and Savior Jesus Christ... "

The truth you know must become your experience, this is only made possible through your confession of faith, express in obedience to the same. So today, start declaring... "I am strengthened with might to walk worthy of the LORD, fully pleasing Him" Etc. You will surely do and see what you say.