A child who at the age of 16 goes through horrifying events causing him to seclude himself to swing a wood cutting ax till the day he dies. Repeating the same motion of bash, side slash, vertical slash, and smash. Sometimes just repeating one move for the whole day. This would go on for 43 years. After the person dies the memories of that moment will Travel back in time to a couple of years before that horrifying moment to help him rebuild himself to be someone amazing.
An Unbreakable Will and Unending Determination. The embodiment of Persistence.
Some changes could be that instead of back in time it could be forward. Or something like awakening past life memories. Becoming a spirit who lives within someone else teaching him what you learn. Taking his view instead of the students like most novels.