''The money,'' he replied.
Lewis is earning every bit of his $450,000 salary. The fourth-round draft pick has been versatile and invaluable as a starter on an offensive line that has been torn apart by injuries.
Drafted 130th overall out of Nebraska, Lewis had no intention learning from the sideline with the hope of garnering playing time as the season went on.
''I don't play football to watch it,'' Lewis said Wednesday. ''When I came here I expected to play.''
Lewis launched his career at left guard against Buffalo alongside fellow rookie Ronnie Stanley, the sixth overall pick and starting left tackle. It marked the first time since 1995 that an NFL team started a pair of rookies on the left side of the line in the opening game.
The pair continued to flourish together until Oct. 2, when Lewis missed the Oakland game with a concussion and Stanley was sidelined with a foot injury. Lewis took over at left tackle the following week.
Stanley still hasn't returned. If he remains hurt this Sunday, Lewis will receive a third straight start at tackle against the New York Jets.
Making the transition from college to the NFL is tough enough. Moving from guard to left tackle - arguably the toughest position on the offensive line - is even more difficult.
''It's a little bit of a shuffle but I played two years at tackle (at Nebraska),'' Lewis said. ''I did a lot of training this offseason at guard, so it's going to take a little bit of adjusting to get comfortable at tackle again.''
Lewis got beat a couple of times in his debut at left tackle and had a costly holding penalty last week against the Giants.
''I think Alex has done great,'' coach John Harbaugh said. ''The thing I like about him is he doesn't repeat mistakes. He improves. He's a smart guy and he works hard.''
Maybe it's in the genes. Lewis' father, Bill Lewis, was a center at Nebraska before playing seven years in the NFL.
''The key to success, not just in the NFL but in life, is learning from a mistake and get better from that mistake,'' Alex Lewis said. ''That's the mentality I have. It's what my father taught me.''
Lewis hasn't been perfect. But the 6-foot-6, 335-pounder has been plenty good enough to make a positive impression on his teammates.
''He's a tough guy. He's a fighter, he's a scrapper,'' center Jeremy Zuttah said. ''With him, it's just about being more confident. He's a rookie, so every game he's going to get better and better. The sky's the limit for him.''
Stanley has a mountain of potential, but at this point Lewis just might be the best rookie in Baltimore's Class of 2016. He's more interested in how he will be perceived in the future.
''To be successful at this level, you've got to be willing to grow,'' Lewis said. ''You can't think that, just because you're playing in the NFL you've made it now. It's, how do I get better, how do I keep getting better, how do I get to be great?''
He could ask Zuttah or Pro Bowl guard Marshal Yanda, but Lewis knows his place - with the rest of the rookies, whose lockers are lined up along a back aisle of the locker room.
''The veterans, they don't want to be bothered,'' Lewis said. ''I'll ask a question if I have to, but most of the time you want to keep quiet around those cats.''
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