FRISCO, Texas -- In the end, Tony Romo opted to walk away from the NFL on his terms.

League sources told Adam Schefter and me that Romo’s decision came down to his health.

Considering all he had to endure from 2006 to 2015 as the Dallas Cowboys' starter, it is understandable why Romo is set to kick off a broadcasting career and not preparing for his 15th season in the NFL.

He played with a punctured lung and broken rib in Week 2 of the 2011 season against the San Francisco 49ers, even attempting to enter the game before the pain medicine took effect. He played the next six or seven games with a Kevlar vest for added protection.

Tony Romo's decision to walk away from the NFL came down to his health, according to sources. AP Photo/Michael Ainsworth

In 2013 against the Washington Redskins, he directed a final-minute comeback with a fourth-down touchdown pass to DeMarco Murray with a searing pain down his legs because of a ruptured disk in his back that required surgery five days later.

In 2010, when he suffered his first broken collarbone against the New York Giants, he attempted to come back into the game only to be physically pulled back by associate athletic trainer Britt Brown. His first question to the head athletic trainer as he lay on the field in discomfort was if his pass resulted in a first down. In 2015, he came back perhaps sooner than he should have from a broken collarbone because the Cowboys' season was heading into an abyss and he re-broke the collarbone.

In 2014, he missed one game because of two transverse process fractures in his back, made it through a Dallas-to-London flight and beat the Jacksonville Jaguars the following week to kick off the best stretch of his career. In the final seven games that season, he threw 19 touchdown passes and was intercepted just three times as the Cowboys finished 12-4.

In 2008, he missed three games with a broken pinkie finger suffered in an overtime loss to the Arizona Cardinals. Amazingly, he was Brad Johnson’s backup for that first game despite not being able to take a snap in pregame warm-ups. He was inactive the next two games and the Cowboys missed the playoffs by a game in a season that was torn apart with internal strife.

He played through other injuries that nobody knew about because he knew his job as the Cowboys' starting quarterback was finite.

He wanted to come back from the most recent injury, a compression fracture in his back suffered last August, to reclaim his job and deliver on what he thought would be his best season, but never got the opportunity. Dak Prescott played too well and the coaches stuck with the rookie quarterback's hot hand.

Romo spent last offseason talking about how good he felt physically and mentally. He told anybody and everybody that he felt like he was at a point where he knew what was coming from the opposing defense and had the answers before the snap. The Cowboys drafted Ezekiel Elliott to take the pressure off Romo the way Murray did in 2014. He had a healthy Dez Bryant and the best offensive line in football.

And then on the third snap of the preseason game against the Seattle Seahawks, he was crunched to the ground. He attempted to come back into that game too, but was held out. As he stood in the locker room after the game, Romo expressed confidence that his back could withstand such a hit and be OK. The next day he learned about the compression fracture.

He would play in only one drive in 2016, throwing a touchdown pass to Terrance Williams against the Philadelphia Eagles.

On April 21, Romo turns 37. He and his wife, Candice, are expecting their third child this summer to join sons Hawkins and Rivers.

Romo could have played another season or two if he wanted. The Houston Texans were a real option with his release upcoming later Tuesday.

Every player has to determine the right time to walk away. For right now, Romo has picked his.

Ultimately, it didn’t end with what he wanted so badly, a Super Bowl ring, but it ended with him giving everything his body could give.