The 58-year-old actress is poised to explore the issue in her upcoming project, which is being published by Flatiron Books.
Shields told PEOPLE: "What we know for sure about women and ageing is that it’s not the put-her-out-to-pasture narrative our society would have us believe.
"I don’t need to hear any more about all the ways my body starts to sag when my ovaries stop working."
Shields’s book remains untitled for the time being. But the brunette beauty has suggested that the creative process will be an educational experience for her.
She said: "I want to know why I suddenly feel this surge of power.
"Why am I finally emboldened to try new things? Why does our culture treat women ‘of a certain age’ like they’re past their prime, while so many other cultures revere their elders? How can we approach this time as the new beginning it really is, rather than the beginning of the end?"
Last year, Shields revealed that she wanted to "change the whole conversation around age".
The actress created an online platform called Beginning is Now, and Shields wants to keep empowering women of all ages.
Speaking about the approach of her company, Shields told PEOPLE: "It's about this demographic of women really coming into their power and owning it and really taking this period of their lives to pivot in the ways they want to - and that's in everything with beauty, wellness - all of it."
Shields expanded into beauty and wellness after launching the brand in 2021.
She said: "I'm just more and more aware of what a privilege it is to be able to exercise self-care and have it be a form of wellness rather than vanity.