IRVING -- A determined Tony Romo sat in front of his locker Monday at Valley Ranch and vowed to return as a "much healthier version" of himself next season to help the Cowboys rebound from a dismal 4-12 finish.

With teammates cleaning out their lockers, some for the final time with the Cowboys, Romo was optimistic while talking about his health and future.

Romo seemed primed for a big season in 2015 as he moved further away from his three back injuries that required two surgeries. But he ended up playing a career-low four games because he twice fractured his left collarbone.

"I'll be a much healthier version going forward actually than I was the last couple of years as my back continues to strengthen and the collarbone will be healed," Romo said. "That'll be easier for me to be in position to do some stuff that I'll be hopefully happy about."

The Cowboys were happy about very little this season when it came to quarterback play. Three backups -- Brandon Weeden, Matt Cassel and finally Kellen Moore -- combined to go 1-11 as the starter.

After the season finale Sunday against Washington, owner Jerry Jones declared that Romo "is irreplaceable."

Romo said he will push himself to make sure Cowboys fans won't have to suffer through another 4-12 season on his watch and instead enjoy another playoff appearance.

"I am going to exhaust myself to ensure that our team is playing these games next year," Romo said.

Romo was sacked only six times in 2015, but two of those sacks forced him to miss a career-high 12 games. He had missed two games over his previous four seasons.

Romo first fractured his left collarbone in 2010, missing 10 games. He fractured his left collarbone in multiple places in the Week 2 win at Philadelphia and missed the next seven games. In his second game back, Romo suffered a hairline fracture to his left collarbone in a Thanksgiving loss to Carolina.

Romo said he would have figured out a way to return for the playoffs had the Cowboys made it this season.

"That's what we play the game for, playing those games," Romo said. "Believe me, we're going to do everything we can to make sure this doesn't happen again."

Romo said he hopes to make a decision by the end of the month on whether to have a plate surgically attached to the collarbone to help protect against another fracture.

"We'll go with a scan and see if [the bone] is improving and make decisions," Romo said. "But there are more options. ... That'll hopefully ensure it becomes very minimal to likely happen again, and that's encouraging."

Romo turns 36 in April and is signed through 2019. He was asked if his best years are still ahead of him and if his body will hold up as he ages.

"A collarbone isn't going to keep me from playing a length of time," he said. "It's not as if there's a huge rehab process that goes into a bone. It just takes time and it heals and it strengthens and then you come back and it's strong. That's how it works."

Twitter: @DMN_George