Rachel Swanson, a registered dietitian at LifeSpan Medicine and author of "Trying!: A Science-Backed Plan to Optimize Your Fertility," splits her time between New York City and Miami, spending about half the year in each. She also takes small-group workout classes three times a week, focusing on strength training. She says eating enough nutrients, especially protein for muscle-building, is crucial for her. She generally aims for around 0.7 grams of protein per pound of body weight, the protein intake usually recommended for physically active people.