– Kirk Cousins has a way of wincing when he smiles, as if even his happiness has been hard-earned.

His isn't the megawatt smile of a sporting hero born for the spotlight. It's a working man's smile — the look of a man who, even amid success, is keenly aware of how far he has still to go.

Outside of his western Michigan hometown of Holland, population 33,000, and Michigan State's passionate fan base, Cousins had never been anyone's hero.

His arrival in Washington was barely noted; he was cast as a career backup the moment the Redskins chose him in the fourth round of the 2012 NFL draft. Until this season, when he supplanted Robert Griffin III as the starting quarterback, Cousins' limited gameday appearances only cemented a reputation for committing costly errors at catastrophic times.

But over the past 10 weeks, the former backup has led the Redskins to a stunning turnabout, following up a 2-4 start with a 7-3 finish that clinched Washington's first NFC East championship since 2012 and a first-round playoff date with the Green Bay Packers on Sunday at FedEx Field.

Cousins was near flawless in that stretch, throwing 23 touchdowns to three interceptions while setting a team record for passing yards in a single season, with 4,166. Cousins credited those achievements to coach Jay Gruden and his staff, gifted receivers, stout protection and every teammate this season.

How did the 27-year-old Cousins become the linchpin of Washington's improbable success?

Mike Shanahan, the former Redskins coach, enumerated the tangibles that initially struck him about Cousins: the arm strength, his accuracy, the array of throws in his repertoire, courage to stand and deliver the ball in the face of onrushing tacklers and the smarts to decode defenses.

Intangibles make a capable quarterback truly special, Shanahan noted.

"It's very hard for people to see from the outside how somebody practices and goes about their business," Shanahan said.

Cousins' study habits and meticulous attention to detail, only intensified over the past two years as he sought new ways to become a better player.

In addition to practice, meetings and weight-room sessions at Redskins Park, Cousins works with a private throwing coach in the offseason. To improve his overall fitness, he also works six days a week with a personal trainer.

"He came in by himself, sat on the couch and said, 'I'm probably the worst athlete on the team,' " Pat McCloskey, director of training at One To One Fitness in Tyson's Corner, Va., recounted of their first conversation in 2014. "He wanted his body and athletic performance to be as efficient and effective as possible. He said, 'If you direct me as to what to do, I'll do the best I can and I'll do it every day.' "

So they launched into a program of dynamic jumps, stretching and resistance work to improve his balance, agility and quickness — which has paid off in five rushing touchdowns this season.

He also sees a chiropractor and an applied kinesiologist weekly and uses a computer-based form of brain training, devised by Michigan-based Neurocore, to sharpen his decisionmaking under pressure.

To improve his time management, Cousins devised a spreadsheet while vying for the starting job in late August that spells out each day's activity in 15-minute, color-coded blocks. He still follows it faithfully.

"There is no entitlement in the NFL," Cousins said. "You've got to prove it every day."