Let us fix our eyes on Jesus, the author and perfecter of our faith, who for the joy set before Him endured the cross, scorning its shame, and sat down at the right hand of the throne of God. — Hebrews 12:2

Jesus isn't just the starter of your faith — He's the finisher. He who began a good work in you will carry it on to completion. It's God who works in you to will and to act according to His good purpose, so your perseverance isn't a product of your grit but of His grip. The Lord will perfect that which concerns you. You didn't get yourself in, and you can't keep yourself in — He does it all.