That principle is

Commit your work to the LORD, and your plans will be established. The LORD has made everything for its purpose. (Proverbs 16:3-4 ESV)

 Our future isn’t limited by our past. No matter what decisions we have made and no matter what point we are at now, the future is still as bright as God’s promises—ones like these: “If you have faith … nothing will be impossible for you,” (Matthew 17:20) and “all things are possible to him who believes.” (Mark 9:23)
 If you’re not where you want to be, there is time to change that. Where there is life, there is hope.
 Film director and producer Orson Welles once said, “A happy ending depends on where you stop your story.” Or as someone else put it, “Everything will be okay in the end, and if it’s not okay, it’s not the end yet.”
 That principle is certainly true for those who love the Lord and look to Him for guidance, because He has promised to always work things out for our good in the end. —M. Fontaine [1]

 I am not what I might be, I am not what I ought to be, I am not what I wish to be, I am not what I hope to be; but I thank God I am not what I once was, and I can say with the great apostle, “By the grace of God I am what I am”. —John Newton (1725–1807)

[1] Anchor The Prize