"It is the duty of all Nations to acknowledge the providence ofAlmighty God, to obey his will, to be grateful for his benefits,and humbly to implore his protection and favors."
-- George Washington
(Thanksgiving Proclamation, 3 October 1789)
Reference: George Washington: A Collection, W.B. Allen, ed. (543)
Although I think football, turkey and family are important as well (not necessarily in that order).