The 39-year-old actress, who is known for her toned physique, believes carrying a child and subsequently looking after a baby on minimal sleep would be tough, so she would want to be in perfect condition.
"If I was having a child I would think that I would want to be the strongest I've ever been in my life. If I was squeezing a baby through my body, if I was going to be carrying it around, it I was going to then be afterwards having sleepless nights, I would just want to be in the best shape of my life," Diaz said.
The "What to Expect When You're Expecting" star, who was most recently romantically linked to rapper P Diddy - would love to have children in the future, and is open to any means of expanding her family.
"I welcome it however it may come, be it through my own body, or if I adopt a child or if I have a partner who has a child," she added.