The 34-year-old "Total Recall" star, who has son Silas Randall, 13 months, with her husband Justin Timberlake, loves being a mother but admits it can be stressful at times, reported Female First.
"It's sometimes hard to find the words [to describe motherhood]. So amazing. So lovely. I'm over the moon. Honestly, I would say motherhood [is the most difficult role I've done]. It's probably the most challenging job in the world, but also the most joyous."
Biel is thankful for the support of her singer spouse. "Justin is a funny, sweet and caring dad - everything and more. I'd call him the perfect parenting partner.