Unable to resume his NFL career because of a back injury that sidelined him for 12 games in 2001, Detroit Lions middle linebacker Stephen Boyd will officially announce his retirement Monday, ending a seven-year career that included two appearances in the Pro Bowl game.

Boyd, 29, first announced last month his intention to retire. He will make his exit official at a press conference in conjunction with the team's invitational golf tournament.

"As much as your heart tells you that you can still do it, your head and your body are the things that determine whether you play," Boyd said last month. "Coming back just isn't meant to be, I guess, and I finally arrived at that reality."

As an unrestricted free agent this spring, Boyd had some interest from other teams, but he could not pass a Pittsburgh Steelers physical exam and clubs backed off after that. During his prime, Boyd was one of the best middle linebackers that fans outside of Detroit knew little about, but his peers certainly respected.

The former Boston College star was selected for the Pro Bowl team in 1999 and 2000.

Boyd joined the Lions as a fifth-round choice in the 1995 draft and he earned a starting job in 1996. He appeared in 86 games, with 67 of them starts, and totaled 773 tackles, six sacks, three interceptions, five forced fumbles and nine recoveries. His 773 tackles rank third in franchise history.

Len Pasquarelli is a senior writer for ESPN.com.