Here’s another reason why exercise is so good for you and why it’s a great habit to start early. It can protect girls from breast cancer at an early age. Why? Because fat is one of the main sources of estrogen, and the more we have the more estrogen our bodies have.
And it’s not too late to start for those at mid-life. We know that there are some breast cancer risk factors we can’t control, ie family history, when we start menstruating or when we begin menopause. But physical exercise and body weight are two risk factors we can change.
A study of 65,000 women shows that regular exercise during the teen years — starting as young as age 12 — reduces the chances of developing premenopausal breast cancer by 23 percent.