Prince William gets nostalgic this holiday season.

The Duke of Cambridge appeared on a special episode of “Time To Walk” for Apple Fitness+, to tell stories from his childhood.

As Hello! reports, Will walked through the Queen’s Sandringham estate, where he stopped by the St. Mary Magadalene Church. The building hosts the annual Christmas Day service the royals attend.

READ MORE: Prince William To Open Up About Mental Health On Special Holiday Episode Of ‘Time To Walk’ By Apple Fitness+

“I have strong memories of walking down here, and my grandfather, he used to walk so fast that there’d be huge gaps and spaces between all of us walking down, and there’d be us at the back with little legs trying to keep up,” he commented. “You know, I think, over time, you start to feel quite attached to those moments and those memories before.”

The royal did feel quite attached to those memories as he shared some details of the service.

“And what’s very good about it is that we sit opposite each other as a family, and growing up, having my cousins sat opposite me has always been quite difficult to keep a straight face at times,” he said.

READ MORE: Prince Williams Reveals His Love Of AC/DC, Children’s Morning Music Rituals

In fact, he couldn’t keep a straight face many times.

“I have had the giggles many, many times in the service. Luckily, no one’s filming it,” Prince William recounted. “So you can get away with it, and on Christmas Day, it’s fun to have a giggle and enjoy yourself.”

The Apple Fitness+ series hopes to encourage listeners to get out and get active to improve their mental health.