Gwen Stefani teases Blake Shelton about his age.

The 41-year-old singer was recently named People magazine's Sexiest Man Alive - but that title hasn't stopped Gwen, 48, from mocking her partner about the aches and pains he's started to suffer in recent years.

Speaking to the publication about his girlfriend, Blake shared: ''I'm younger than Gwen. And lately, things like, I don't know, gout, and a back going out. Or my knees are constantly bothering me. Those are things she's like, 'Aha! How do you like that? You're 41 now, Blake.' She teases me about my age.''

Blake has become more conscious about his age in recent years, which has led him to spend more time in the gym and generally take better care of himself.

Despite this, Blake admits he struggle to maintains his self-discipline.

He explained: ''I think I like exercising more than I ever have, just because I know that it's easy for it to get away from me at my age now.

''But I've never been good at it. You can see pictures of me, it is what it is. I'll lose a bunch of weight and feel good about it and what do I do when I feel good? I eat. Then next thing you know, some picture comes out of me and I've got three chins.''

Meanwhile, Gwen recently claimed that the sexiest thing about Blake is his heart.

The 'Used To Love You' hitmaker said: ''It's interesting because I don't think any of those things like beauty or sexy or whatever way you want to describe humans is necessarily a physical thing that people are attracted to.

''It's all about the heart, and he has that big ol' gigantic heart in there, so he's quite an attractive human. I'm not the only one that thinks it!''