The actress, who is a soon-to-be grandmother of three, told Us Weekly at the premiere that she doesn't "diet or anything."
"I just happen to like reasonably healthy food and I actually haven't worked out for about three weeks," she said. "I worked out today for the first time. I was walking around country lanes in England in the cold so that burnt off a few calories," the British star explained. "But I was also eating quite a lot of Maltesers [chocolate candy], so I'm not quite sure how that works."
How does she keep herself motivated through a workout?
"My motivation is that I like to be able to move my body around," Seymour told Us. "I've had back surgery and injuries, so for me -- as much as anything -- it's a question of really being mobile and I'm just so grateful that my body's working. I do Pilates, Gyrotonics with weights -- I do a specific workout that's good for my body."
And laughter is always excellent medicine. The actress told Us she had "way too much fun" filming Freeloaders.
The Wedding Crashers star plays "one of those nasty real estate, pushy Beverly Hills ladies" in the comedy. She shared, "I had a crazy platinum wig that I picked up and decided to wear at the last second."