The Brady Bunch star says Henderson was like a "second mom" to him

Christopher Knight is mourning the loss of his TV mom, Florence Henderson, who died Thursday at the age of 82.

“I may have lost a cast mate, a good friend and a role model, and really my second mom — but so did the rest of America,” Knight, best known for his role as Peter Brady in the hit sitcom The Brady Bunch, exclusively tells PEOPLE. “We all lost her in the same way. Everybody is mourning in the same way.”

Adding, “Her opinion mattered. Pleasing her and having her respect and her guidance is something I always sought. I didn’t always get my guidance from her directly or verbally, but just through watching her and by letting her guide me through behavior.

“For a long time, she probably didn’t know how much she meant to me. I didn’t even know what I was doing — there was some difficulty in my own family with my own mom — and I had an alternate mom that I could use at moments when my own wasn’t working for me.”

BRADY BUNCH, Christopher Knight, Florence Henderson, Barry Williams, Mike Lookinland, 'The Grass Is

Henderson died surrounded by friends and family at Cedars-Sinai Medical Center in Los Angeles after suffering heart failure, the actress’ manager Kayla Pressman said in a statement to the Associated Press on Thursday. She was hospitalized just a day prior.

The TV matriarch, who became a second mom to Knight during their days on The Brady Bunch, was a woman of great magnitude, he says.

“She was a person who I did not want to disappoint,” shares the actor, 59. “You want to shine for her. She would get the most out of you. I don’t know how she did that, but she did. I’m really grateful that she was in my life. She provided a role model and a great deal of entertainment.”

The Brady Bunch
Summer TCA Portrait Session 2014, July 2014
Credit: Maarten de Boer/Getty

Knight, who recently got married for the fourth time to Cara Kokenes in November, says Henderson welcomed his new bride with open arms.

“She totally approved of Cara,” he says. “It was wonderful having her make her part of the family.”

Though Knight last saw Henderson at a taping of Dancing with the Stars to support fellow Brady Bunch costar Maureen McCormick, he admits he wishes he had seen her more often.

“Spending time with Florence was time well spent,” he says. “You just felt great after having spent that time. That’s how we felt. We went to dinner with her after and every time I spend time with her I say, ‘We have to do more of that.’ That’s the regret I have. That was the last time I had that opportunity. There wasn’t nearly enough time spent with Florence.”

Though Henderson is no longer with us, Knight says he will honor her to the best of his ability.

“Trying to live like her is how I’ll try to honor her — having respect for all,” he says. “Let’s all be as kind as Florence was.”