Lady Eliza Spencer in Bathing Suit is "Life Goals"

Lady Eliza Spencer's boyfriend Channing Millerd is clearly still head over heels for the model and socialite after six years together—and he's happy to share those feelings on his social media. Millerd posted a picture of himself and Spencer lounging on the beach in a black bikini, gazing lovingly at each other. "Life goals," a fan commented. How does she stay so fit? Read on to see 5 ways Spencer stays in shape and the photos that prove they work—and to get beach-ready yourself, don't miss these essential 30 Best-Ever Celebrity Bathing Suit Photos!

Spencer enjoys taking long walks in the park, especially when she's in London. "Walking can help protect you during cold and flu season," says Harvard Health. "A study of over 1,000 men and women found that those who walked at least 20 minutes a day, at least 5 days a week, had 43% fewer sick days than those who exercised once a week or less. And if they did get sick, it was for a shorter duration, and their symptoms were milder."

Spencer and boyfriend Millerd enjoy paddle boating on the Thames. "I take many of my individual clients and classes outdoors," says certified fitness instructor ShaNay Norvell. "They often tell me it doesn't feel like as much of a workout as running on the treadmill, even though they are still getting a great calorie burn. Many people feel a lot of tension about working out, losing weight and lowering their blood pressure. Outdoor exercise is enjoyable and feels more like play than a chore."

Spencer enjoys melon and prosciutto as a delicious snack. "Melons are not only low in calories and fat, but they are also high in essential vitamins and minerals, and water content," says UPMC Health. "In fact, a fresh watermelon, cantaloupe, and honeydew contains up to 90 percent water, making them some of the most thirst-quenching snacks around. And serving them is simple as can be. All you need is a knife and a plate and you'll have yourself a poolside favorite."

Spencer loves fresh salads, especially with cucumber. "Like any vegetable, cucumbers have health benefits, and even if they may not be as well-known as say, kale, it doesn't mean they aren't there," says Jessica Perez, RD. "They can help with weight loss in the sense that if you fill up more on them, you'll be less likely to eat junk foods since they can be a very filling food," says Perez.

Spencer is an avid horseback rider, and has been for years. "Riding a horse for 45 minutes at a walk, trot and canter can burn up to 200 calories," says Dr. Dennis Sigler, a Texas A&M AgriLife Extension Service horse specialist and professor in the department of animal science at Texas A&M University in College Station. "If you do something a bit more strenuous such as cutting or reining, that can come out to nearly seven calories per minute for the entire length of the riding period."