The 39-year-old singer and actress says that while having three children age 7 and under is certainly difficult, she and husbandEric Johnsonhave learned how to tackle it together.

“Three kids is no joke. It is definitely constant, and the biggest challenge for me is trying to be present when I am pulled in so many directions,” she tells PEOPLE in this week’s issue. “They are all in such different phases now.”

The star’s oldest child, 7-year-old daughterMaxwell “Maxi” Drew, is embracing life as a social butterfly with a passion for animals, while sonAce Knute, 6, is “obsessed with sports,” Simpson says.Birdie Mae, meanwhile — like most 3-month-olds — keeps her focus on drinking milk and taking naps.

“There is a lot of dividing and conquering going on right now at our house,” Simpson reveals of parenting with Johnson, 39, who is a former NFL player.

Jessica Simpson/Instagram

Jessica Simpson on Easter

Jessica Simpson Baby Birdie

John Shearer/Getty

Jessica Simpson

“We typically download a movie and order dinner or do somethingsuper low-key to just connect,” she tells PEOPLE. “Eric is the greatest motivator and connecting with him on morning walks is the most grounding part of my day.”

The fashion designer frequently offers fans glimpses of her home life on Instagram, showing off personal moments that feature thingslike Birdie’s adorable dimplesand Maxi and Ace’s skills as older siblings.

“Birdie is so precious. She is a little smiley angel these days. It is the best thing in the world to see and feel her smile. It fills the room,” Simpson says.

Jessica Simpson Baby Birdie

Jessica Simpson.Dimitrios Kambouris/Getty

Jessica Simpson

RELATED VIDEO:Jessica SimpsonShares Adorable New Photos of 4-Week-Old Birdie with Daughter Maxwell and Son Ace

As if having a household full of children wasn’t enough, Simpson has even more on her plate, witha memoir for Harper Collinsdue out in February and the launch ofJessicaSimpson.com, a sales destination for herJessica SimpsonCollection that doubles as a place for the star to share stories, ideas and photos.

For more onJessica Simpson, pick up the latest issue ofPEOPLE, on newsstands now.

source: people.com