Jessica Biel feels "unsexy" as a mother.

The 40-year-old actress is married to pop star Justin Timberlake and has sons Silas, seven, and Phineas, 21 months, but joked that motherhood is the most unattractive job "in the world" even though it is still "the best."

She said: " [Being a mom] is probably the No. 1 most un-sexy job in the world for the most part. It's the best job, most days, and then it can be such a challenging job!"

The '7th Heaven ' actress added that she likes to go on date nights with' Cry Me a River' hitmaker Justin, 41, even though it can be "hard" to find a balance.

Speaking on 'The Today Show', she told hosts Hoda Kotb and Jenna Bush Hager: "But I think it is important to go on date nights. You have to take the time for yourself. It's so hard. I'm trying to take my own advice. I'm not good at it and I'm still working on finding that balance in my life."

Meanwhile, Jessica explained that she is bringing her children up to be "curious" about the world around them because it is "so important" to learn about other cultures and that she herself is a "constant student".

She added: "[I'm trying to teach them about] Being curious about the world, being curious about other places you're not from, that you have never been to. That is important to me. "I am a constant student of the world and I hope my kids have that same love as well.