The actress and Neutrogena brand ambassador talks to PEOPLE in this week’s issue about her current self-care routine — both physical and mental

Jennifer Garner is embracing every precious year of life.

In this week’s issue of PEOPLE, the 51-year-old actress and longtime Neutrogena brand ambassadoradmits that even though she has her “moments” where she reflects on her younger years, “Honestly, mostly, I am grateful just to be alive.”

“And I’m grateful for the wisdom that I’ve gleaned out of these years and really grateful to be able to watch other women go through this process of life so gracefully,” Garner adds.

She also says she tries “to follow in their footsteps and tell other young women, ‘Take care of yourself, but don’t be scared. Aging is a gift.’ ”

As for what her own personal self-care routine looks like, the 13 Going on 30 actress tells PEOPLE she works out “every day,” as “it’s super important for my mental health.”

“I eat really well. I just finished a big bowl of kale,” she continues. “And I have a really strong family and strong relationships in my life.”

The mother of three — who shares Violet, 18, Seraphina, 15, and Samuel, 12, with ex-husband Ben Affleck — says she also allows herself to “have down days.”

“I don’t try to be Pollyanna all the time,” Garner says. “And I’m gentle with myself.”