Joe Theismann has just completed what he describes "as the best three weeks of training camp I've over had." But he also knows "the facts of life on this football team.

"No matter what happens in the next six weeks," he said today, stoically, "I think I have a pretty good idea what will happen in the season opener. If Billy Kilmer is healthy, he's gonna play. There's no sense kidding yourself.

"But I do believe both of us are going to be needed, and I've accepted that for the first time in the four years I've been here. I've changed a lot, my thinking has matured. And for the first time since I've come here, I feel a part of this team, not just a fixture on the wall."

The answer come quickly and effortlessly. And perhaps you have heard many of them before from this gifted athlete - a shrewd young man with a natural knack for self-promotion.

He has parlayed his good looks, his flashy playing style and his keen sense of public relations into a gold mine of opportunities.

He has an adoring public, a successful restaurant and part ownership in a car dealership, and a lucrative and long-term contract with WJLA-TV.And yet, he said, "it won't mean a thing unless it goes right with football. That's all I ever really wanted.

There is something else he covets, as well. It is called respect, and it has been the most elusive goal of all for Theismann.He also knows why.

"When I first came here," he said, "it was always Sonny-Billy or Billy-Sonny, I wanted to belong, and I forced myself on people. I think the only guy I was fooling was myself. I guess maybe in the beginning I did alienate people.

"It was my manner, and my approach. Now don't get me wrong. I was being me, and as I look back, I'm not sure I would change a lot of things. But I have matured and I have learned there are times to say things and times not to say things. It all boils down to taking care of your own business.

"Your peers recognize you not on what you say, but on what you do. How do you react in the touch situations, how do you perform under pressure. Until you prove your worth, it's a tough thing to be accepted.

"In other years, I'd feel like there was a certain group of guys who wouldn't even say hello to you because you just didn't belong. Maybe a lot of it had to do with my brashness or loudness. I don't know, but I think that's changed."

Theismann also perceive a change in his relationship with his chief rival, Kilmer, I don't believe there's the coldness there once was," he said. "I hope there's sort of a breaking down of the barriers. I don't know why. I can't speak for Billy. But this year seems different, and I hope it continues."

Certainly, last season was different for Theismann. He was given an opportunity to start five times and play for extended periods in two other games in which Kilmer was physically unable to perform.

His performance in a must-win game at San Francisco - three touchdown passes and 302 yards in the air - went a long way toward silencing his detractors. But there was that Giant step backward two weeks later in the New Jersey Meadowlands, an interception which very nearly ruined the season, and an injury that forced Theismann back to the bench.

Theismann admitted he will remember that interception "for a long, long time." But he also believes that staying in the football game despite a very painful hip pointer incurred in the first quarter has had far more lasting and significant consequences.

"In any other city on any other team, I would have come of that game," Theismann said. "But Billy and I have completed - at least in my mind we completed - for three years, and playing behind that man and seeing him do the things he's done, well, I just could not leave the game.

As long as I could stand, as long as I could still throw, and no matter how much pain I felt, it made no difference. If you're going to be a part of this team, you have to be as a tough mentally as all of these other guys.

"The fact that I threw the interception was not the reason I didn't play the next week, I couldn't throw the ball more than 15 feet without it feeling like somebody was pouring hot coals on my left side. After we got to St. Louis, I got five shots. Eight days later I started to get the feeling back."

There is still numbness in the area, Theismann said, but nothing that has affected his throwing or his running in the first three weeks of camp.

"I can't ever remember throwing the football any better," he said. "In the last three weeks, I've made maybe four throws that I knew were wrong when I threw them.

"Every pass I've thrown has been thrown with a reasin or a purpose - something I wanted to see, to try, to experiment with against a certain kind of defense."

Theismann is negotiating a new contract with the club. He and his agent, Ed Keating of Cleveland, have given the Redskins a proposal and are waiting for an answer. Theismann is believed to be asking for a long-term contract that would also put him in the same salary category as Kilmer.

Theismann would seem to have all the leverage in this affair. He can play out his option and after his services to the 27 other clubs, or he can head back to Canada, where, he says, a million-dollar deal has been offered by his old team in Toronto.

"All you have to do is take a look around the league and can see how many quarterbacks are needed," he said. "And next year, with a 16-game schedule, every team is going to need at least two guys who can start.

The way I understand it, there has also been a bona fide offer from Toronto. I had a lot of fun up there, and it's nice to know they haven't forgotten.

"I'd like to stay here, certainly. It's taken me a good four years to learn this system. Not just the Xs and Os, but the whys and the wherefores. I've adjusted my thinking to this system.

"Sure, you could be a rebel and try and fight it, but you'll also alienate a lot of people. If you sit around and mope instead of concentrating on doing your job, when you do get the chance you've been so busy griping, about you'll go out on that field and look like an idiot.

"I have no doubts in my mind that I could start anywhere else, but I don't really want to play anywhere else. I believe in the same things this organization believes in, I believe in training for 12 months. I believe in winning. And I believe in enjoying the success of your teammates."

And this year he also believes his teammates are going to enjoy Joe Theismann's success, as well.

The lump on Diron Talbert's chest appears to be responding to treatment. "They're giving him penicillin," Allen said today. "We'd like to treat it without surgery if possible." . . . Pat Fischer spent another day in traction in the Carlisle Hospital because of his sore back, but he said the pain had subsided and "I hope I can get out of here today or tomorrow." . . . Tight and Jean Fugett sat out today's single practice session because of a sore back, but he is expected to be available for Monday night's preseason opener against the Browns . . . Linebacker Joe Harris was back in camp after visiting his ailing mother in Fayetteville, N.C. He immediately made his presence felt by smacking rookie running back Mike Northington to the ground on an aborted sweep . . . The Redskins will practice in Carlisle Sunday afternoon, and will leave for Cleveland Monday morning.