1 Thessalonians 5:16-18

Rejoice always and delight in your faith; be unceasing and persistent in prayer; in every situation (no matter what the circumstances) be thankful and continually give thanks to God; for this is the will of God for you in Christ Jesus.  

We need to keep ourselves built up and consistent as Christians. The practice of our faith should be continuous and not just now and then. We have more power against the enemy when we keep our prayers up and our minds renewed. Prayer and thanksgiving are our barriers against the knocks of the world through our faith in God.