Ben Roethlisberger wanted to quit. 

The date was Sept. 21, 2008. The game was against the Philadelphia Eagles, a game that saw Big Ben, then in his fifth season as the Pittsburgh Steelers starting quarterback, endure eight sacks in a 15-6 loss. The pain inflicted on Big Ben that day actually made him privately ponder how much more he wanted to play football. 

"I'm not a big 'remembering games' type guy, especially losses, but that's one that I do remember vividly," Roethlisberger said back in 2016 when asked about that game. "I remember getting sacked eight or nine times. I remember driving home from the airport after that game and thinking to myself like, 'Do I want to keep doing this? Do I really want to keep playing football?'"

The answer, obviously, was yes, even though Big Ben did publicly contemplate retirement at the end of the 2016 season. But this offseason, Roethlisberger, entering his 16th NFL season, signed a contract extension that will keep him with the Steelers through the 2021 season. While he will be just shy of his 40th birthday when his current contract expires, team president Art Rooney II has not ruled out the possibility of Big Ben remaining the Steelers' quarterback well into his 40s. 

Here are the three reasons why Roethlisberger may very well play into his 40s, something that seemed extremely unlikely a decade ago. 

A vastly improved offensive line 

Roethlisberger found himself on the ground a lot during the first half of his career. From 2006-09, he was sacked 189 times that included a league-high 50 times in 2009. As Gerry Dulac of the Pittsburgh Post-Gazette recently mentioned, Big Ben's 501 career sacks are the third-most in NFL history. He's 25 sacks away from Brett Favre's all-time record, a record Roethlisberger is not in a rush to break. 

The sacks started leading to injuries; Big Ben missed a quarter of the season in 2005 and played in all 16 regular-season games just once in his first nine seasons. A nagging injury handicapped his effectiveness in one of the worst losses of his career, the Steelers' stunning upset loss to Tim Tebow and the Broncos in the 2011 wild-card round. 

Pittsburgh has since surrounded Big Ben with arguably the NFL's best offensive line, a line that consists of potential future Hall of Fame center Maurkice Pouncey and fellow perennial Pro Bowlers David DeCastro and Alejandro Villanueva. The Steelers' line also consists of Ramon Foster, a former undrafted rookie back in 2009 who has evolved into one of Pittsburgh's most reliable starters. Pittsburgh made Big Ben happy this offseason when they extended the contracts of both Pouncey and Foster. 

A man who has played an essential part in Big Ben's resurgence is Mike Munchak, the Steelers' offensive line coach from 2014-18. With Munchak presiding over Pittsburgh's offensive line, Big Ben was sacked just 144 times while earning four of his five career Pro Bowl selections. And while Munchak left Pittsburgh this offseason to take the same position in Denver, Shaun Sarrett, Munchak's longtime assistant, has seamlessly replaced Munchak as the Steelers' new line coach. 

The Steelers have also added depth to their O-line in recent years. Matt Feiler, a former undrafted rookie, has replaced Marcus Gilbert as Pittsburgh's starting right tackle. Pittsburgh is hoping that Chukwuma Okorafor, a third-round pick in 2018, can emerge as the team's top swing tackle in 2019. And while nothing in the NFL is certain, it appears that Roethlisberger should continue to have a strong offensive line for the duration of his career. 

Finding the right offensive coordinators 

Roethlisberger wasn't happy when the Steelers decided not to renew Bruce Arians' contract following the 2011 season. Not only did Big Ben enjoy success with Arians as Pittsburgh's OC (the Steelers won Super Bowl XLIII with Arians in that role while advancing to another Super Bowl in 2010), the two developed a close bond that continues today. 

The beating Big Ben took in Arians' offense led to the Steelers hiring Todd Haley during the 2011 offseason. While Haley was never as close to Roethlisberger as he is to Arians, his offense -- along with his emphasis on getting Big Ben to get rid of the ball quicker -- greatly reduced his sack totals while helping produce four of his biggest passing seasons. Roethlisberger tied for the NFL lead in passing yards in 2014 and led the NFL with an average of 328 passing yards per game in 2015. Haley's offense also helped Big Ben and the Steelers compile a 13-3 regular-season record in 2017 before Pittsburgh was upset by Jacksonville in the divisional round. 

Pittsburgh replaced Haley with former quarterbacks coach Randy Fichtner during the 2017 offseason. Like Haley, Fichtner's offense is predicated on quick passes designed to better protect Pittsburgh's franchise quarterback. Fichtner, like Arians, has also established a bond with Roethlisberger that certainly increases Big Ben's odds at playing into his 40s. 

The Steelers have replenished Big Ben's play-makers 

Pittsburgh has done a stellar job giving Roethlisberger several young play-makers that will likely be with him for the remainder of his career. While Antonio Brown and Le'Veon Bell are gone, the Steelers still have Pro Bowl talent in JuJu Smith-Schuster and James Conner. Conner amassed 1,470 all-purpose yards and 13 touchdowns last season, while Smith-Schuster -- the team's MVP last season -- led the Steelers with 111 receptions for 1,426 yards. Second-year receiver James Washington seems poised for a breakout year in 2019, while rookie widout Diontae Johnson also appears to have serious star potential. 

The Steelers' defense, the team's weak link five years ago, has the potential to be one of the NFL's top units over the next several years. The fact that Pittsburgh's roster -- as a whole -- should be good enough to contend for a title for the foreseeable future is definitely a reason why Big Ben is now considering playing into his 40s. 

Bonus reason 

The fact that Roethlisberger remains driven to win another Super Bowl is a major reason why he will remain under center for the Steelers for at least three more years. In fact, Big Ben said during camp that is more motivated than ever to bring another Vince Lombardi to Pittsburgh. 

"I feel like I love football again," Roethlisberger told the Post-Gazette. "I told my wife when I was home the other day, she was asking how it was going. I said I feel like I love football again. She got a big smile on her face and said it made her happy to hear that."

Steelers fans are also happy that Big Ben, despite his previous retirement scares, is ready to help lead Pittsburgh on another championship run before hanging up his cleats for good ... whenever that ultimately may be.