Human beings, by changing the inner attitudes of their minds, can change the outer aspects of their lives. The greatest discovery of my generation is that a human being can alter his life by altering his attitudes of mind.
William James (1842 - 1910)

I am still determined to be cheerful and happy, in whatever situation I may be; for I have also learned from experience that the greater part of our happiness or misery depends upon our dispositions, and not upon our circumstances.
Martha Washington (1732 - 1802)

Most folks are about as happy as they make up their minds to be.
Abraham Lincoln

A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort.
Herm Albright (1876 - 1944)