Gwen Stefani's secret for looking youthful? Making out with her fiancé, Blake Shelton.

During a chat with The Daily Telegraph's Stellar, the 51-year-old singer discussed beauty and why Blake is the one to thank for her agelessness. "Blake is the greatest guy," she gushed, before explaining how he's had a positive impact on her physical appearance. "I look back over the past few years and look at pictures of when I first started kissing Blake, and I look the best I've ever looked in my life in those photos. Love must look good on me. I feel like that does show through – it really does."

After releasing the music video for her song "Let Me Reintroduce Myself," in which the pop star revisited the most iconic looks from her career, people couldn't get over the fact that she hadn't aged a day in more than 20 years. Even Blake admitted that he doesn't know "how it's scientifically possible to look how she does."

"People talking about my aging is a compliment, I guess," Stefani said about the recent public interest. "I'm kind of obsessed with how I'm aging, too." However, she did acknowledge the associated pressure.

Gwen continued, "It's really hard for everyone to age and have to face life. Especially for females and people who have been in the spotlight it can be daunting, but you tackle it by just trying to be the most beautiful version of yourself inside and out."

In addition to kissing Blake, Stefani's skincare routine is relatively simple.

She washes her face every night before bed, and makes a point to get all the makeup off before applying a moisturizer. "I don't have a huge routine, but I wash my face with some cleanser that takes makeup off. I just recently started using these pads from a dermatologist that takes more makeup off. I cannot believe how much makeup was on there for all those years," she told InStyle back in 2017. "I think about [when I was on tour] on a bus, trying to wash my face in that little sink. That's what I did forever!"