It may be the last thing that anyone struggling with breast cancer is thinking about, but it's important: Get some muscles.

A new study published in JAMA Oncology finds that women with breast cancer who have more muscle mass have a better chance of survival.

In general, when people aren’t well, they can lose a lot of weight, and much of that weight is muscle. Low muscle mass also often occurs as we age, and it seems to correlate with poorer outcomes in people who are chronically ill, including those who suffer from cancer.

The study included 3,241 women from Kaiser Permanente of Northern California and Dana Farber Cancer Institute, who were diagnosed between January 2000 and December 2013 with stages II or III breast cancer.

Higher muscle mass meant a lower risk of death, regardless of a woman’s age or cancer stage, the researchers found.

The takeaway for women, whether they have breast cancer or not, is to build more muscle.

A good diet -- particularly one with protein -- helps build healthy muscle. Good sources of protein include lean meat, eggs, yogurt, fish, beans and nuts. The recommended daily allowance of protein is based on your weight. A women who weighs 125 pounds needs about 45 grams of protein in a day.

That would be about 3 ounces of chicken and 3 cups of milk in a day. Another way, it’s 4.5 ounces of salmon and 100 almonds.