"Most folks are about as happy as they make up their minds to be.”
- Abraham Lincoln, American elected head of state in the 1860s
N.B. This quote is apparently misattributed to Lincoln, according to the website Mental Floss. The quote gained traction because in 1914 a guy named Frank Crane wrote a newspaper article that attributed the quote to the President.
Image Source: Lincoln Memorial, Washington, D.C.