The 41-year-old actress said on Thursday's episode of Lorraine that she "would never change" her decision to wed and have children in her 20s.
"It's about that next chapter in your life," Witherspoon said of her new movie Home Again. "What do you do when you're 40 and you made a decision when you were 25 to get married and have kids?"
"I got married when I was 23 and I had two kids by the time I was 27," she remarked. "I don't know, sometimes it's good to know yourself [first]. I would never change anything."
Witherspoon and Phillippe, who share 18-year-old daughter Ava and 13-year-old son Deacon, split in 2006 after seven years of marriage. Phillippe said in an interview with Larry King in 2015 that he believes he and Witherspoon married too young.
"No, I think more of the problem was age," the star said after King asked if the split was due to the pair both being actors. "We got together so young."
Witherspoon married Jim Toth in 2011, and shares 5-year-old son Tennessee with the talent agent. Phillippe told People in December he's "open" to getting married again, but confessed it's challenging to date in the public eye.
"[Fame] affects those in your life who didn't choose to be a public figure: your children and the people you are in a relationship with," he said.