FRISCO, Texas -- One day at training camp in Oxnard, California, maybe two or three years into DeMarcus Ware's career, he was going through a pass-rush drill in which he had to run around a hula hoop and turn the corner as low as possible.

As he took his strides, he bent low with his left arm dragging on the ground. As he reached the end, he sprung out of the stance and delivered a blow to a tackling dummy.

A higher-up in the Dallas Cowboys scouting department was within earshot and said to nobody, "Wow, he's just a panther."

The athleticism was astounding. The speed was a blur. The power seemed to make the ground shake. He made it look so effortless.

That's my lasting image of Ware.

Ware, 34, officially announced his retirement Monday after 12 years in the NFL, nine with the Cowboys and three with the Denver Broncos.

A week ago, Ware was contemplating another season and had looked at the Cowboys as a real possibility, a way to tie a bow on his Hall of Fame career. Had he joined the Cowboys, he would be their best pass-rusher. But as he said via Twitter, "long term health and quality of life outweigh the spark and passion to play that I once had."

Ware is the Cowboys' all-time leader in sacks with 117. He stands eighth all time with 138.5. Every retired player ahead of Ware on the sack list will be in the Pro Football Hall of Fame, with Jason Taylor earning enshrinement this summer. Julius Peppers, who has 143.5 sacks, signed up for another year, returning to the Carolina Panthers.

I covered Taylor and the Miami Dolphins for three seasons, when he had 41.5 sacks from 2000-02. He used his undersized frame but incredibly strong hands to frustrate offensive linemen and quarterbacks. His speed around the edge was ridiculous. It seemed like he could run with a receiver.

Ware did the same things in his career. He was built to be a 3-4 outside linebacker. When the Cowboys drafted him, Bill Parcells, who was said to have wanted Marcus Spears with the No. 11 overall pick, immediately compared Ware to Lawrence Taylor, so the coach's anger could not have lasted long. And he got Spears with the 20th pick, so all was OK with Parcells anyway.

Ware was named to the Pro Bowl seven straight years with the Cowboys (2006-12). He was a seven-time All Pro for Dallas. His most memorable game with the Cowboys came in December 2009 -- a week after he left the field on a stretcher, unable to move because of a neck injury -- when he sacked Drew Brees twice and Dallas ended the New Orleans Saints' run at a perfect season.

The Cowboys released Ware after the 2013 season. His salary-cap figure was too high and he was coming off a six-sack season. A day after he was released, he signed with the Broncos. With Von Miller, he formed one of the best pass-rushing duos in the NFL, winning a Super Bowl in 2015. In the AFC Championship Game against the New England Patriots that season, he could not be blocked.

He missed time last season because of a fractured forearm. In January, he had surgery for a back issue that has troubled him for years. He said he felt great and wanted to play again, but he came to the difficult decision to walk away while he could actually walk away.

Hopefully Ware will sign again with the Cowboys.

It will only be ceremonial, but it will be forever.