ET caught up with the actress and lifestyle mogul at BeautyConLA at the Los Angeles Convention Center on Saturday -- where she was joined by her 6-year-old daughter, Maxwell -- and she opened up about her happy, adoring relationship with her handsome hubby.
"He keeps me hot, I have to say," Simpson shared.
The celeb recently celebrated her 38th birthday on July 10, and she celebrated the special occasion with a super sultry, fiery red -- which she shared a photo of to Instagram on her special day.
"I wanted to have fun, to feel sexy and it's like, OK, 38, what are we going to do to celebrate 38? Let's have red hair," Simpson explained.
However, more than just the hair, she said her desire to stay healthy and youthful is motivated by seeing how energetic and excited her husband is, especially around their adorable kids.
"He's always throwing around the kids, and he's just an amazing father, it makes me want to stay young," Simpson shared. "Like how can you be so active? I mean watching the kids running makes me exhausted."
While the pair are absolutely devoted to their two children -- Maxwell and their 5-year-old son, Ace -- Simpson reiterated that they are content with the size of their family as it is.
"Were good, we are chilling," Simpson shared. "I mean we're very happy and we know how to make babies very well but, we got the little one here."
Maxwell tagged along with her mom, and Simpson called the event a "definite bring your daughter to work day."
"It is all about beauty and my daughter is just as obsessed with hair and make up and entertainment, as I am," she shared.
The proud mom also said that her little girl gave her some much-appreciated input when designing some new products, explaining, "She has helped me along the way. It's good to have an opinion from a 6-year-old, we all need a little youth."