Reality star Jill Duggar takes her fitness, and her faith, very seriously.

So much so that instead of listening to workout music, the soon-to-be mum chose to use the OnePlace app to listen to a sermon by inspirational speaker Pastor Rick Warren.

In her recent Instagram post, followed by 975,000 users, Jill shared a selfie of her on a treadmill with the caption "Walking at the gym this morning while listening to a sermon by Pastor Rick Warren on the #OnePlace app!"

Jill, who stars in the reality show 19 Kids and Counting, following the lives of the growing Duggar brood, is now 28 weeks pregnant with her first child and has taken to social media many times to express her excitement over motherhood.

Since learning of her pregnancy, Jill has periodically posted pictures with her baby bump while holding up signs marking her progress.

In an interview with US Weekly, Jill confessed that she and her husband Derick Dillard were initially very surprised when they learned that they were expecting because their first two pregnancy tests yielded negative results.

The third test, which she took at her parents' home showed a different result.

"We were super excited. We prayed together, and thanked God for this new little life. I was screaming and everything. [Derick] was like, 'Don't get too excited! You might stress out the baby or something.' He's so cute. He's so sweet," Jill said.

During her pregnancy, Jill has shared some sweet and funny pictures, including one where she asked her husband to taste a sour pickle she had a craving for.

 "@derickdillard made this cute face when I gave him a super sour pickle! #papadilly #sourpickle #funnyface."

She also occasionally posts sweet messages about her newlywed bliss: "It's been 200 days since my best friend and I @derickdillard said "I do"! I'm blessed beyond measure!'"

The post was accompanied by Bible verses about love.

Last November, the couple shared ultrasound images of their baby and announced that they were expecting a boy in March.

In an article in People magazine, Jill said: "I am keeping his ultrasound pictures safe - it is so exciting to look at this picture. He is moving and kicking now, and it's crazy to realize I have this wonderful baby boy inside me.'

Jill and Derick were married last June 21 in Arkansas in front of 1,000 guests where they shared their first kiss. They now live near the main Duggar household in Tontitown.