David Letterman, who hosted late night talk shows for 33 years until 2015, says he should have left 10 years earlier

David Letterman has had a long, illustrious career in late night television — but he actually wishes he had cut it a little shorter.

Appearing on The Ellen DeGeneres Show on Thursday, Letterman, 71, reflected on his many years of hosting, which began in 1982 with Late Night with David Letterman on NBC and ended 33 years later with the Late Show with David Letterman on CBS in 2015.

“Here’s the mistake I made — I stayed on television way too long,” he told Ellen DeGeneres, 61.

“That’s not true,” she said.

“Yes, it is true,” he insisted. “And I’ll tell you what happened: It turns out, nobody had the guts to fire me. I should have left like, 10 years ago. You want to make sure you have some energy to direct towards other things. Now you, nothing but energy, are doing other things while you’re on television, so that’s great. I did not.”

“All I cared about was myself and then the show was gone so I had to realize, oh, I’ve been looking through the wrong end of the telescope. There is more to life than, ‘So tell me about your pet beaver,'” he continued.

Last year, Letterman resumed his hosting duties in a different capacity with the six-episode My Next Guest Needs No Introduction with David Letterman on Netflix, which consists of interviews with one high-profile guest per hour-long episode. Season 1 featured Barack Obama, George Clooney, Malala Yousafzai, JAY-Z, Tina Fey and Howard Stern.

RELATED VIDEO: George Clooney Tells David Letterman About His Deep Love for Wife Amal

Netflix confirmed a six-episode season 2 in December. Letterman confirmed on Ellen that DeGeneres will be a guest.

“You know, it’s great,” he said. “And the reason it’s great is first of all, the Netflix people have been very generous to let an old man anywhere near their building.”

The Ellen DeGeneres Show airs weekdays (check local listings).

Season 1 of My Next Guest Needs No Introduction with David Letterman is streaming on Netflix. A premiere date for season 2 has not yet been announced.