Very well known.  and very good medicine! I have observed that a lot of anxiety , depression and unhappiness results from  an un willingness to accept it when things go pear-shaped. When we can accept that things have gone pear shaped with serenity, then without all the stress we can make clear decisions, and find the courage to make necessary changes- to improve a situation or to walk away from it- that’s where the wisdom comes into the picture!