'Bachelorette' alums Kaitlyn Bristowe and Shawn Booth talk fitness, birthday fails and taking things slow

What's the secret to Shawn Booth and Kaitlyn Bristowe's super-fit physiques? Pizza.

Okay, not exactly. But the "Bachelorette" alums, who found love on season 11 in 2015, know the importance of taking much-deserved breaks from demanding diet and exercise schedules. While Kaitlyn doesn't take her workout regime quite as seriously as Shawn -- "I really do not like going to the gym," she flat-out admitted -- her fiance, a personal trainer, isn't opposed to Kaitlyn's Sunday pizza dinners.

"I'm a big fan of cheat meals. I give myself one to two cheat meals a week," Shawn told AOL Entertainment. If you're thinking that your cheat meal cadence is more like five to six times a week, don't feel too bad: Shawn is on a particularly strict regimen as he trains for IRONMAN Lake Placid this July.

"It's super intense right now," Shawn said, adding that it's often painful to get out of bed because his body is so sore. "I try to get [Kaitlyn] to give me massages, but today she just booked one for me, so we had a massage therapist come to the house. So I got a nice deep-tissue massage."

The professional massage was in part a birthday present, as Shawn and Kaitlyn spoke to AOL Entertainment on Shawn's 31st birthday -- although hours earlier, Kaitlyn mistakenly bought him giant "32" balloons.

"I went to Party City and I was thinking about what age I was turning!" Kaitlyn explained, laughing. They both shared photos of the unfortunate mixup: "When my fiancé woke me up this morning and said "Happy Birthday! Do you feel 32?!" I thought she was joking," Shawn wrote. For her part, Kaitlyn captioned the photo, "Fiancé fail."

Shawn and Kaitlyn recently celebrated what they affectionately call the "longest engagement ever," but they're not complaining: "We're just trying to do it the right way, if there is a right way," Shawn said. "Being on TV and getting engaged after barely knowing somebody isn't really ideal. Once we got off the show we just wanted to take our time to get to know each other before we take that next step."

Added Kaitlyn, "I don't really feel like much has changed [between us] except for the fact that we get more comfortable with each other. Now it's a normal relationship where I'm like, 'Okay, can we spend more quality time together? You're at the gym twice a day and then you want to sleep.'"

For these two, there's just hardly enough time in the day: Kaitlyn is busy with her new podcast, Off the Vine, and Shawn teamed up with personal trainer Erin Oprea to found CitySTRONG, which hosts large group workouts across the country and contributes proceeds to different charities.