Richard Simmons' Close Friend Marc Summers Says He Understands Why Fitness Icon Lived in Seclusion (Exclusive)

Marc Summers is one of the many people mourning the loss of fitness guru and personality, Richard Simmons . The pair, who each appeared on their own respective television series, had a friendship that spanned decades.

In a new interview with ET, Summers reveals he hadn't spoken to Simmons in over a decade -- but that doesn't change how he feels about his late friend, who chose to live the final years of his life out of the spotlight. Simmons died on July 13 .He was 76 years old.

"I hadn't seen Richard in over 10 years, and sadly tried to get in touch with him but [he] was not talking to anybody," Summers tells ET's Kevin Frazier. "We had mutual friends who actually knew him even better than I did. And he just chose not to go back out into the public. And I'm not sure what he was doing with his life other than chilling and relaxing."

"Other than his publicist, who I guess he spoke with on a regular basis, I heard he was still living alone," he continues. "I believe his brother is still around and I don't know if he saw his brother at all. I don't think he interacted with many people at all, perhaps on the phone. But as I say it's been over 10 years so I haven't had any interaction with him. And I gotta tell you, I truly missed him."

Summers doesn't know exactly why Simmons chose to live out of the spotlight. But he has a theory, given that Simmons gave so much of himself during the height of his fame.

"He would go out of his way to walk up to people who he didn't know, asked how they were. He was concerned about other humans," Summers says. "And when I heard about the reclusive situation towards the end, I understood it and I'll tell you why. Nobody gave 120 percent of energy like Richard did. And I just think he was exhausted after putting in all that time, that he needed some time to himself. And actually I'm really glad he got that. We all missed him and wanted to interact, but but he needed his own space."

He continues, "He always thought about others. When he was in a crowd, you knew he was there. But he would come up to people and go, 'Where are you from? Tell me about your life.' He was more interested in others and wanted to know their personal stories. And it was sincere. When he would make these regular phone calls on daily basis, they weren't one time phone calls. He would follow up on these people on a regular basis. He made a lot of money, good for him, but he spent a lot of money on others by flying to their houses, and by treating them in various ways and holding their hands and talking to them and was sincere and will look them in the eye. I don't think I've ever met anybody else who had that kind of personality and I'm not sure there ever will be another person as strong and important on this planet as is Richard."

When it comes to Simmons' legacy, Summers says it will span far beyond Sweating to the Oldies , and his comedic late night and television appearances. Simmons will be remembered for his genuine and kind heart.

"The kindness that I saw in him with other people in hotel lobbies and airports, where people don't walk up to strangers and start conversations. Richard Simmons did and he cared and he somehow had the sixth sense where he knew people needed him," Summers tells ET. "And he could feel that and walk up. And all of a sudden there was a 20-minute conversation with a perfect stranger, often taking phone numbers and saying, 'I'm going to call you.' I think most people didn't believe that. He was sincere. He was honest. And as I say, I I can't think of one person I could compare him to."

If Summers could say one final thing to his late friend it would be, "I love you. And thank you for doing what you did and for helping all the people that you did, and applauding him."

Another person with a close working relationship to Simmons was Patrick Leonard, who was collaborating with Simmons on songs for the potential show about his life.

"It's all very autobiographical, and it's all all very determined to tell the story, you know. from his point of view," Leonard tells ET. [It was] things about the beginning, things about his early days of putting his own place together to start his own exercise programs. And how he felt about it, and how the people felt about it. Things about his love of records, his love of listening to records, and how that inspired him."

While Leonard didn't communicate face-to-face with Simmons, he says they spoke everyday. The musician fondly remembers a moment early in their collaboration that warmed his heart and showed him who Simmons truly was.

"One thing that was that was interesting and charming and just pretty beautiful is from the beginning, he said, 'I'm never going to call you anything other than Mr. Leonard.' I never heard him say my name. He just said Mr. Leonard and my wife is Lady Anna," he says. "And it was beautiful because it felt like this is what he wanted it to be. And so it was. He's incredible man, incredible human being."

Leonard tells ET that Simmons' legacy is in the lyrics that they wrote together, and has hopes that he world will hear and see his story one day.

"People know what he gave them because they could see it palpable and real," he says. "I guess we'll just have to wait till we get it on the page.I think the consensus amongst everyone on the inside of this inner circle is that it should go on because it was his dream.I find myself in a position of being someone who is pretty much convinced himself I wasn't going to collaborate anymore of being the keeper of the flame for this beautiful man's legacy."

Leonard's latest project, "It All Comes Down to Moon," it out on July 26.

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