One of the most iconic superstars in WWE history made his on-screen debut at the 1990 Survivor Series. This Sunday, 30 years later, The Undertaker will be at Survivor Series once again to participate in his "Final Farewell."

The Undertaker (a.k.a. Mark Calaway) has not been featured on WWE television since defeating AJ Styles in a Boneyard Match at WrestleMania 36 in April. While it has been clear for years that Calaway was ready to hang up his boots, he told CBS Sports this week that he's still coming to terms with an official retirement.

"I'm kind of going through a whole gambit of emotions, really," Calaway said. "I'm honored that WWE has taken this effort to honor me in this whole month with the docs and other things. It's really humbling that a company would do that. Not knowing exactly what the show is going to entail, I'm looking forward to hopefully seeing some of the guys I've worked with through the years there. It's definitely going to be bittersweet for me. It's one of those deals where I feel it's important that I'm there and get to address the fans and people who have been with me for 30 years and followed my career and stuck with me when it's been a flavor of the month business for a long time.

"It's going to be very emotional. It's all going to become very real that my career in the ring is likely over. I'm just running that whole spectrum of emotions and trying to encapsulate everything and keep everything in check.

For years, it looked like Calaway had hit the end of the road. He struggled through big matches, physically unable to do the things that set him apart as one of the most athletic big men in the history of the business. But then, he would have a surgery or two, come back and impress -- sometimes even surprise -- fans. So the question continued to hang in the air: Will The Undertaker ever retire?

"The thoughts were already in my head that it was drawing near. I think the icing on the cake was the Boneyard Match this year. I'm very proud with how that turned out and all the reviews it got, but it was at the end of that night, and actually in the early morning, and how I felt physically," Calaway explained.

"Here you are, it's all over now and you're walking like an 85-year-old man. It was just letting me know that the tank was pretty much empty. As bad as I hate to say that, it's just reality because none of us can outrun Father Time. In the big scheme of things, I'm relatively still a young man, but in the world of professional sports and entertainment, I'm obviously in the twilight of my career. It became painfully obvious that my time had come and it was time for me to, as they say, put my six shooters up on the mantle."

After losing to Roman Reigns at WrestleMania 33 in 2017 -- one of the matches Calaway struggled through physically -- he left his gloves, hat and jacket in the ring, an apparent signal that it was his final match. However, he returned to the ring for eight additional matches before the Boneyard Match with Styles in early 2020. That will, officially, serve as his final match. Calaway said that both the Reigns and Styles matches had their benefits when considering what defines his final bout.

"You know, I guess it's one of those apples and oranges kind of things," Calaway said. "That was so honest and pure and just where I was at on that night when I left my hat and coat and gloves. I had no intention of coming back, and it felt like that was the organic thing I needed to do. At that point, I can't get on the microphone and give some long speech about thank you and this and that. It just didn't work for that character. I said all I needed to say by putting that stuff in the ring and walking out. It was just my pride after many months that got in the way and said, 'Aw, man, you just can't go out like that.' The physical performance, I just couldn't bring myself to leave on that note. I had the surgery, fixed my hip and got after it.

"The Boneyard was so cool in the fact that you got a little bit of everything. You got a little bit of the original Undertaker, you got a little bit of the American Badass, and you got a lot of Mark Calaway in that. Like I said, it's apples and oranges and whether you're a traditionalist and there's a lot of people who say you should always lose your last match. You're not going to make everybody happy. I knew after the Boneyard that it was time to call it a day. I don't know. It's all up for interpretation which way you think is better. I don't have a clear-cut thought of the way I should have done it. It just happened this way and we are where we are."

The Boneyard Match served as The Undertaker's final official bout. WWE

Wrestling is a notoriously difficult pursuit from which to step away. Shawn Michaels has been one of the few to retire and seem content with his decision. Michaels recently spoke with CBS Sports about his legendary matches with The Undertaker and shared his hope that Calaway could find that same contentment in retirement.

According to Calaway, the retirement will stick for good -- even if WWE chairman Vince McMahon may have other plans.

"You know, I have to deal not only with my thoughts and my conscience, but I also have to deal with Vince's thoughts and his conscience," Calaway said. "A lot of times, they're not always on the same page. Vince's line is, 'You never say never.' But where I'm at, I don't see myself getting to a point where I'm going to be physically better in a couple of years than I am now. I'm going to be a couple of years older and a couple of years slower. So yeah, I mean, I just don't see it. Not in the capacity where I'm going to get in the ring and actually work. Whether I have some sort of role, that's a different thing, but my days in the ring I think are long gone now."

It's on that note that we wonder: If "The Undertaker" is retired, could we see Calaway in another capacity? A forthcoming WWE Hall of Fame induction will simply a matter of timing. Perhaps there will be occasions where Calaway will be used on television to further others' storylines or provide expertise ahead of matches. The Undertaker may not fight again, but one should not expect Calaway to disappear from WWE TV for good.

"You are always linked to it once you're in this business -- especially when you're in it as long as I've been in it, you're linked to it forever," Calaway said. "I actually enjoy going to the Performance Center and working with the young guys. I can definitely see myself doing that. If there's a role for me somehow that makes sense on camera, I'll cross that bridge when I get there. I do know it's extremely difficult for me to be at an event that I'm not working at because I just have that natural instinct that I should be getting ready right now or doing this. If I'm sitting there watching a monitor with other talent, I get caught up in it.

"The only reason I'm calling it a day is simply because I don't have the physical tools to do this at a level I want to do it. The passion is still there, and if I could, I would do this forever. But that's not a reality, and that's now how that works. You have your run and your time. I was blessed with an extremely long run, and I need to be happy with that and move on to whatever comes next. I'm not stepping away because I want to or I'm burned out or anything like that. I'm just physically spent, and I have to think about the rest of my life and the quality of that life."

Calaway said that he has nothing he looks back at from his career and wishes went differently other than that he wished his programs with Steve Austin and Eddie Guerrero lasted longer. But even those desires are minor in a long and storied career that saw him emerge as not just a superstar but as a respected "locker room leader" backstage.

While he has only been around the locker room sporadically in recent years, Calaway did say that it's easy to see the ways the backstage environment has changed from his peak.

"It appears to me that it's more of an individualist locker room now," Calaway said. "Everybody kind of does what they want to do and there isn't that governing body that kind of keeps everybody together. I could be wrong. I'm not there enough to give a real insightful answer. That's just the way it appears to me. I see guys with leadership qualities, I just don't know it's being exercised to the extent that it was back in the day. That's not to say it's good or bad, that's just how it is. The business evolves and the locker room evolves. Sometimes that's for the better, sometimes for the worse. We'll see what happens, but it doesn't feel as tight-knit as it used to."

The locker room, like the WWE, will continue go forward as it evolves, adapts and changes to the times -- for the first time in decades without Taker among its ranks.

As for what life looks like on Monday morning when Calaway wakes up as an officially retired wrestler?

"It looks like a big old fat turkey at Thanksgiving, and from there, I hope to get back to Texas, head up to my ranch and go hunting and just spend as much time out there enjoying nature and doing what country folk do. Then, as the new year comes along and hopefully we kind of get a handle on this COVID-19 deal and things get back to normal, hopefully interjecting myself into the Performance Center and seeing what other opportunities are out there for The Undertaker."

WWE will hold The Undertaker's Final Farewell on Sunday at Survivor Series. The event will air at 7 p.m. ET worldwide on the WWE Network.