The entertainer became a father for the fifth time in 2004, when his fourth wife Jodie Brooke Wilson gave birth to their first child.
Speaking to Hello magazine, the 80-year-old dismissed suggestions that it had been "selfish" of him to have another baby.
O'Connor explained: "I want to be with him for as long as I can, and that's another reason to keep myself in good shape. I don't have a strict health regime but I do think you have to take care of yourself. I've never drunk heavily but I drink even less now.
"I exercise but nothing too strenuous. I try to keep myself in good nick."
However, O'Connor admitted that he did have some concerns, saying: "I think I'm more worried that Adam might be concerned one day that his dad is a bit older than everybody else's.
"Happily, though, I'm not experiencing that at the moment. I had people saying I was selfish. But what's selfish about that? How can you say to a woman you've been with for 15-odd years, 'No, I've got four and we're not having any more?'. That would be selfish."
Discussing the 37-year age gap between himself and Wilson, he told the magazine: "There are no rules, no regulations, no time limit on love. You either want to be with someone or you don't."
> Des O'Connor: 'I may become a father again'