He destroyed the quarterback record by over a 100 games, but that doesn't begin to say how great this streak is.
In the NFL, losing a start is not only due to injury, it's also due to declining abilities.
Quarterbacks are benched every season—many in fact—so to start every game means you are a proven great quarterback, or you have a juicy new contract. And even then, to do it for over 10 seasons is insane.
Roger Goodell, the commissioner of the NFL in recent years has pussied up the league to create more safety for the quarterback position. Brett Favre made his first start in 1992, so this does not heavily apply to the 40-year-old active quarterback.
Oh yes, he's 40, an age most athletes lose their muscle mass and go on Jenny Craig diets, not throw for over 30 TDs and lead their teams to conference championships.
It's no wonder that in that time, Favre broke every conceivable career passing record, but that's for another list.