So what's their secret?
"There's no real trick," Duff told E! News at the 2014 Teen Choice Awards. "We're both doing so well that I'd rather not talk about it because it's old news. But we both care about [our son] and being the best parents we can be is our main focus."
And at 2 years old, Luca continues to surprise his proud parents with everything he does.
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"There's no word good enough to describe how he's changed my life and how amazing he is," she told E! News. "He's so much fun and it's amazing to watch him grow. Week by week he changes so much."
When not spending time with her precious son (and getting sprayed in the face with a garden hose), Duff is hard at work on her new album.
If you liked "Chasing the Sun," then you may just love her upcoming single, "All About You."
"It's a super summer song," Duff shared. "I wrote it with an amazing writer/producer named Savan Kotecha and he's like a pop genius so it will be good."
We can't wait to hear it!
For more scoop from the 2014 Teen Choice Awards, watch E! News tonight at 7:00 p.m. and 11:30 p.m.