Josh and Anna Duggar will soon be adding another baby girl to their growing family, and the couple can't help but feel both excited and overwhelmed with a new baby on the way.

"Is there pressure? Sure, there is. But one of the biggest blessings is to have kids and teach them to serve God and others and be the best they can be," Josh told PEOPLE. "You can have a career, and be famous and have lots of money, but that will fade. Children will be there."

He added that they are open to having as many children as God plans to bless them with, but he cannot wrap his head around the idea of having a family as huge as his parents Jim Bob and Michelle, of 19 Kids and Counting fame.

"I've done the math, and there is no way we can have 20 kids that I can figure," he said. "But the reason most people don't have a large family is because they feel the financial pressures. It's tough to have so many kids in today's world."

Anna said that things will definitely get busier the more children they have, since children are a huge responsibility. "But it is a happy busy," she quickly added. "There is no better way to invest my life, my body and my time than to my children."

Josh and Anna's children are also pretty excited to meet their new baby sister. Mackynzie really wanted a sister so she was thrilled with the news, while Michael wanted another boy. Marcus, on the other hand, remained mum.

"Mackynzie made a recording saying, 'Hi, little sister, it is so great to meet you, you are already my best friend,'" shared Anna.

And despite his initial preference, Michael has accepted his new sibling's gender. "I am happy the baby is a girl," he said.