Professional athletes rarely, if ever, want to see their careers end, but when the time eventually comes, ideally they'd prefer it be on their own terms. Not everyone is afforded that opportunity, of course, and even when they are, they don't always seize the moment.

Rob Ninkovich is someone who did.

"There's something to be said about going out on top," he told a packed gathering of media, teammates, coaches, staff, and family at Gillette Stadium Sunday while officially announcing his retirement from the NFL.

Smiling and collected at the outset, Ninkovich went on to thank numerous people important to him in his life and career, but started to lose his composure when addressing defensive coordinator Matt Patricia, seated nearby. The two men evidently shared a strong personal and professional relationship, with Ninkovich crediting Patricia for bringing out the best in him as a player. Both men struggled to contain their emotions as Ninkovich spoke.

"Coach," a choked-up Ninkovich then said directly to head coach Bill Belichick, "I gave you everything I had. I hope it was enough… I love it here, and I'm going to miss it."

That Ninkovich ever enjoyed a career in the NFL at all is a remarkable story. While playing at junior college, he recalled having to pester his eventual head coach at Purdue more than a dozen times before he was even granted a recruiting visit. To help him prepare to play major college football, Ninkovich also enlisted the help of Daniel "Rudy" Ruettiger, the former Notre Dame player whose life story was immortalized in a popular Hollywood film. When Ninkovich finally enrolled at Purdue, he began as a tight end before switching to defensive end.

After two solid seasons at Purdue, Ninkovich was a legitimate NFL Draft prospect in 2006, and actually thought he was going to be selected by the Patriots. The New Orleans Saints plucked him with the 135th overall pick in the fifth round – one spot before New England – but just three games into his Saints career, Ninkovich suffered a season-ending knee injury. He spent the next two injury-plagued seasons being signed and released several times by the Saints and Miami Dolphins.

When New Orleans released him yet again in the summer of 2009, the Patriots finally came calling, and ever since, his career flourished. Initially, there was some question about whether Ninkovich was best suited as a defensive end or outside linebacker in New England's system, but the Patriots knew they had a "special guy," as head coach Bill Belichick referred to him during introductory remarks Sunday.

"He's Croatian, so, I knew he was tough," joked Belichick, who is also of Croatian heritage. He proceeded to laud Ninkovich for his on-field versatility, durability, play-making ability, and leadership, then embraced Ninkovich before turning the microphone over to him.

Ninkovich recalled his first training camp practice, during which he drew the coaching staff's attention by beating then-starting left tackle Matt Light on three consecutive plays. However, it was his special teams coverage abilities – and skills as a back-up long snapper – that won Ninkovich a job on the roster that season. The next season, he became a regular starter on defense.

While injuries marred his first three seasons in the NFL, Ninkovich enjoyed a mostly healthy career as a Patriot, starting all 16 regular season games from 2011-15, including playoff contests and Super Bowls, while being elected a team co-captain on a couple of occasions. After serving a four-game NFL suspension to start last season, he returned to start 11 of 12 games and help the Patriots capture their fifth Super Bowl title this past February.

By then, the 33-year-old married father of two had apparently begun pondering his future in football. He took part in the team's offseason program, including spring practice sessions, and in remarks to reporters earlier this month seemed to indicate that he was looking forward to another season. When he failed to appear on the field at the start of training camp last Thursday, it took many observers by surprise.

In his press conference Sunday, Ninkovich indicated he ultimately decided to listen to his body, not his heart.

"When you're trying to build back up, when you're younger, I feel like you're OK and you're feeling OK," he explained. "For me, I was trying to build back up and felt like I wasn't where I needed to be, to be what I am and what I feel like I should be, for my teammates and fans.

"I was honest with myself. You have to be honest with yourself. I feel like athletes sometimes get away from that because they don't want to believe what they're telling themselves, but I knew that my time was probably close."

Throughout his Patriots career, Ninkovich became popular among teammates, coaches, and fans for his hard-working attitude and determined playing style. He also earned a deserved reputation as a sought-after spokesman for media interviews and as "a great ambassador in the community," which was how owner Robert Kraft described him.

So, what next for Ninkovich? He told reporters he would take some time to decompress, but didn't rule out pursuing a career in the media. Ninkovich also mentioned several times that he wouldn't be a stranger to Gillette and that coaching could be in his future as well.

"I'm so grateful for the Patriots organization," he concluded. "Man, it's been so much fun."

A 'Marvelous' day

After Sunday's full-pads practice, Kraft brought a guest out onto the field. It turned out to be former world middleweight boxing champion "Marvelous" Marvin Hagler, who was invited to Foxborough to speak to the Patriots later in the day. In advance of the visit, Belichick played a highlight reel of Hagler's greatest hits the night before.

"Generally, when that happens, guys kind of learn how to get mean really quick," Hagler told reporters as he left the field. "They seem to be very appreciative of it… I've been a big fan of the Patriots for a long time."

The New Jersey native lived for a while in nearby Brockton, Mass., where he first started boxing in 1969. Hagler still has a home in New England, but currently resides full-time in Italy, where he earns a living as an actor.

Stock Watch

Buy: Chris Hogan – Consistently one of the best receivers over the first four days of camp.  

Sell: Ryan Allen – The normally reliable punter struggled for the second consecutive practice.

Play of the Day: During goal-line work in an 11-on-11 period, RB Brandon Bolden appeared to have a clear path to the end zone when FB James Develin opened up a hole for him on the right side of the formation, but LB Elandon Roberts came flying in from the side to drop Bolden short of the goal line with a powerful tackle.

The Patriots will take Monday, July 31 off before resuming training camp practice on Tuesday, August 1.