Simplify the following text for a Grade 7 native English-speaking person.
Original: Walter Payton ( July 25 , 1954 â `` November 1 , 1999 ) was an American football player who spent his entire professional career with the National Football League 's Chicago Bears .
Simplified: Walter Payton ( July 25 , 1954 â `` November 1 , 1999 ) was an American football player .