Tony Scheffler is retiring from the NFL.
Scheffler told The Associated Press on Wednesday that having three concussions over the past four years had "a lot" to do with his choice.
He had 258 receptions for 3,207 yards and 22 touchdowns in his eight-year NFL career.
The Detroit Lions released Scheffler in October.
He later had workouts with Chicago and Kansas City and says there was "moderate" interest in him as a free agent this off-season.
Denver drafted him in the second round in 2006 out of Western Michigan and traded him four years later to Detroit.
Scheffler says his plans include becoming a real estate agent and assistant football coach at the high school in his hometown of Chelsea, Mich.