I see this quote from time to time on social media:
You can’t go back and make a new start, but you can start right now, and make a brand new ending.
The quote is attributed to everyone from Zig Ziglar to the Philadelphia Eagles, but according to Quote Investigator, it is originally from a book by James R. Sherman titled Rejection: How to Survive Rejection and Promote Acceptance. (How ironic to have your authorship of a quote about rejection rejected by the internet!)