Shailene Woodley on Adopted Pets Deserving a ‘Grace Period’ (Exclusive)

Shailene Woodley knows the care and comfort that must come with being a pet parent to a new furry friend.

The actress, 33, is helping raise awareness for pet adoption during Mars’ Global Adoption Weekend. In an exclusive interview with PEOPLE, she opens up about finding a forever home for animals and why a “grace period” is necessary, in order to allow them time to adapt to their new lives.

“When you bring an animal home, don’t assume that it’s going to be immediately symbiotic — things take time, relationships take trust and patience. It’s the same way for animals and humans,” Woodley says.

“Anyone in a long-term healthy relationship knows patience, understanding and grace are required, and bringing home a shelter animal, there must be a grace period too, of being patient and understanding that this animal comes with its own set of history and its own life that it lived before you, and you come with your own history and life you’ve lived before it,” she continues.

Adds the Big Little Lies star: “That establishment of trust, of being slow with the process of gaining their trust and giving your trust, I think sets up a relationship that will only ever be productive and comforting for all of the parties involved.”

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Woodley has been an animal lover her entire life. The first pet she ever claimed as her own was a small black cat named Kitten that she adopted as a teenager.

“She was the best,” the Emmy, SAG and Golden Globe-nominated star recalls of her feline friend. “This cat would play fetch, and she was playful and snuggly. I could hold her in any position and she would just purr. I was her person. She was constantly attached to my hip.”

“I just remember at 16 years old, having the responsibility of her, and her alone, to feed her, to clean her litter box, to make sure she was hydrated, it felt like an entrance into adulthood, and it gave me a sense of knowing that this animal was literally dependent on me,” Woodley adds.

“But then [there was] also my dependency on her and her greeting me at the door, or her being there when I’d come home from school. I was also working full-time on a TV show at that point in my life, so knowing that I’d get to come home and lay with her, it took away any teenage angst or anxiety I might’ve had,” she continues.

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Woodley is currently a cat mom to two felines. “His name is Bear, her name is Pharrah, and it’s the first time I’ve ever had sibling pets,” The Secret Life of the American Teenager alum tells PEOPLE. “And honestly, it feels like a game-changer for them — and for me.”

“When I’m at work, I’m not worrying if one of them is at home alone and lonely and just waiting for me to walk in. Knowing they have each other, to entertain and comfort one another, [is great],” she continues.

“The affection that they share extends into the affection that they share with me, and the affection I share with them. And with them, I feel like anything is possible,” adds Woodley.

“I don’t feel alone. I don’t feel lonely anymore. I feel completely taken care of, and there’s nothing to complain about at all in my personal life, because I have this unconditional love and affection from them,” the pet mom reiterates.

Woodley’s first cat Kitten and all the others she has had since have inspired her to always adopt shelter animals — and she hopes to share that mindset with others.

“So often these shelters are running off of donations from other people,” she says. “I feel like shelters and the people who work at them are unsung heroes.”

Woodley has teamed up with Mars and Calm to raise awareness for pet adoption for Global Adoption Weekend, which takes place from Oct. 3 to Oct. 5. One shelter the actress is proud and excited to highlight is Animal Haven in New York City, which is holding an in-person adoption event over the weekend.

“My hope is that people, regardless of whether they choose to adopt or not, are open to visiting a shelter or to accompany a friend or to have a conversation or educate themselves more,” Woodley says. “Using this weekend as a muse for that opportunity just feels important to me to encourage people to participate in, [because] you never know [what might happen].”

She adds: “I did not think I was bringing two cats home the day I brought two cats home, and I cannot imagine my life without them.”