Carrie Underwood wasn't sure she wanted to have children.

The 37-year-old singer and her husband Mike Fisher are parents to Isaiah, five, and Jacob, 16 months, but the 'Before He Cheats' hitmaker admitted she and the 39-year-old former hockey player had different ideas about family when they first met.

While Carrie never saw herself ''getting married or having a family'', Mike wanted to replicate his own idyllic childhood.

Carrie explained: ''I was never good with other people's kids. Why would I be good with one of my own?''

And Mike said: ''I grew up with three other siblings and I had a great mom and dad. I think that I just wanted something like.

''I wanted to be the best dad, to be like my dad and have a wife like my mom, have kids and [live] in the country.

''I got everything and more than I dreamed of to be really honest.''

But the 37-year-old fell ''in love'' as soon as she had her oldest child, though it was tinged with fear.

Speaking on the couple's new four-part show 'Mike and Carrie: God & Country', she said: ''It's just this tiny person that you're just trying to keep alive in the beginning.

''The first time I held Isaiah, I thought, 'What did we do?' ''

While the couple have been together for more than a decade, Carrie admitted she ''never'' expected to end up with someone like Mike.

She explained: ''He grew up hunting and being outdoors, and it's a big part of his life. I grew up on a cattle farm, and I went the other way.

''I don't eat meat and do my best to not buy leather things. I love animals, I love life so much that I always swore I would never marry a hunter... not in a million years.

''We just differ drastically. We learn from each other and we have [discussions] about things we disagree on but at the end of the day, we love each other very much.''

But no matter their differences, the couple will always have their shared faith.

Mike said: ''That's where our faith comes in, too. It's kind of that centre ground, where that's the most important thing in anything.

''I know your heart, and I know my heart.''