Too many people think about faithfulness as being some kind of a thing that they must work up. But faith is a gift of God. You just have to depend on the Lord to keep you faithful, and trust Him that your faith won't fail. Faith comes from Him.
All you have to do if you don't have enough faith is just hear the Word, read the Word. That's the source of faith. (Rom.10:17) You have to give Him a little cooperation, listen, read and obey, but that's the easy part. It's His job to keep you faithful, full of faith!
So quit trying so hard! Quit worrying about it! Quit trying to work it up or even pray it down! Just keep trusting the Lord, and He'll give you all the faith you need!
"Now unto Him that is able to keep you from falling, and to present you faultless before the presence of His glory with exceeding joy, to the only wise God our Saviour", commit your way, your life, your mind, your thoughts, your time! "For I know Whom I have believed, and am persuaded that He is able to keep that which I have committed unto Him against that day." (Jude 24,25; 2Tim.1:12) Praise the Lord! Only He can do it!