Jason entered NFL as an undrafted free agent. The resourceful back has 43 career receptions for 254 yards and 2 touchdowns while adding 12 carries for 41 yards in five NFL seasons. He has appeared in 45 career games through his first five NFL seasons while spending time on the rosters of Philadelphia and Dallas before coming to Chicago in 2003. Jason has started in all four postseason appearances while gathering six receptions for 16 yards with one carry for three yards resulting in his first career rushing touchdown. He became the Bears full-time starting fullback in 2006, responding with career highs in receptions (25) and receiving yards (162) in 15 games played, while starting 12 and signed 5-year contract extension (11/2/06).