A wonderful article about ways to learn and exert yourself better by Susan Krauss Whitbourne Ph.D. shows how we grow to be self-critical and doubting. Moreover it describes how one could overcome this inner demand to make ourselves better and better. It doesn’t mean one doesn’t need to change, but this recess may be not so endless and very tiring.
I truly recommend you to read it. https://www.psychologytoday.com/blog/fulfillment-any-age/201604/10-ways-learn-yourself-better