There are two kinds of worries -- those you can do something about and those you can't. Don't spend any time on the latter.
Source: In The Speaker's Electronic Reference Collection, AApex Software, 1994.
-- Duke Ellington, (Apr 29 1899-1974), US bandleader, songwriter; He was an outstanding jazz personality who wrote over 5000 original works, e.g., Take the 'A' Train.