Vitamin D: Over the past decade, dozens of studies have revealed many important roles for vitamin D, the nutrient that skin cells produce when they are exposed to sunlight. The recommended daily intake of Vitamin D is 600 IU per day, although recommended levels are under review. If you avoid the sun or live in the northern half of the U.S., ask your doctor whether your vitamin D level should be tested.
“The reason most people don't see changes isn't because they don't work hard—it's because they don't make their workouts harder,” says Adam Bornstein, founder of Born Fitness. His suggestion: Create a challenge every time you exercise. “Use a little more weight, rest five to 10 seconds less between sets, add a few more reps, or do another set. Incorporating these small variations into your routine is a recipe for change,” he says.
In the past, women have often tried to make up deficits in their diet though the use of vitamins and supplements. However, while supplements can be a useful safeguard against occasional nutrient shortfalls, they can’t compensate for an unbalanced or unhealthy diet. To ensure you get all the nutrients you need from the food you eat, try to aim for a diet rich in fruit, vegetables, quality protein, healthy fats, and low in processed, fried, and sugary foods.
It's easy to get lost in a killer playlist or Friends rerun on the TV attached to the elliptical, but mindless exercise makes all your hard work forgettable—and you can forget about seeing results too. “There is a huge difference between going through the motions of an exercise and truly thinking, feeling, and engaging the key muscles,” says Kira Stokes, master instructor at the New York City location of indoor cycling studio Revolve. “Be conscious of and enjoy the sensation of your muscles contracting and the feelings of growing stronger and more powerful with each rep.”