Celebrity Parents How Katherine Schwarzenegger Will Include Daughter Lyla in Yearly Tradition with Sister Christina New mom Katherine Schwarzenegger chats with PEOPLE about how her sister Christina "is a very involved auntie" to her daughter Lyla, 3 months By Jen Juneau Jen Juneau Twitter Jen Juneau is a digital news writer for PEOPLE since 2016. People Editorial Guidelines and Hanna Flanagan Hanna Flanagan Style + Beauty Assistant, PEOPLE People Editorial Guidelines Published on November 17, 2020 03:00 PM Share Tweet Pin Email Katherine Schwarzenegger can't wait to pass on one of her favorite family holiday traditions to her 3-month-old daughter, Lyla Maria. In an exclusive chat with PEOPLE surrounding her partnership with Aerie for the brand's #AerieREAL Kind Hotline Campaign in honor of World Kindness Day, the new mom opens up about how she and her family are "still trying to figure it out" in terms of the holidays amid the ongoing coronavirus pandemic. Going forward, though, the author and activist has big plans for her and her baby girl during her "favorite time of the year" that involve Katherine's younger sister, Christina. "I always traditionally do a sleepover with my sister the night before Christmas Eve. I'm hoping that that's something that I can continue doing and bring [Lyla] along to do it, which will be fun," says Katherine, 30. Katherine (L) and Christina Schwarzenegger. Stefanie Keenan/Getty "She is a very involved auntie. So that's a fun thing that I like to look forward to," she adds. "Then also we spend Christmas with my whole family and we're at my mom [Maria Shriver]'s house and my dad [Arnold Schwarzenegger] comes over and we all meet there and spend the whole day there. And we're just together, which is my favorite time of the year." Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories. Katherine Schwarzenegger Is Already Decorating for the Holidays: "I'm a Huge Christmas Person" While The Gift of Forgiveness author has "already started decorating for Christmas," this year's holiday celebrations will undoubtedly "look different for everybody," including her, husband Chris Pratt and their extended family, given the current health climate. "Los Angeles is having a really big spike in [COVID-19] cases right now ... and obviously my family's biggest concern is always making sure that everybody stays healthy," Katherine shares. "[My family] are big mask-wearers. They practice social distancing and they're really good about all of that, especially having a newborn around." "I think we have to wait to see as we go along because the numbers and the situation of what's going on in the world seems to change every day," she tells PEOPLE. "So it's figuring out what's the safest and most realistic way of being able to be together, but also being able to be safe. And then also focusing on what matters, which is just being able to be grateful for our health and for life and celebrate that." As she looks back on 2020, though, Katherine says it has been "incredibly exciting" in that she has become a first-time mom, which was "obviously life-changing" and "a really interesting time to be pregnant." RELATED VIDEO: New Mom Katherine Schwarzenegger Finds It 'Comforting' Husband Chris Pratt Is Already a Dad "It was and is the greatest role and joy of my life. I feel really blessed to have had that be the biggest part of my year and also a really exciting time in my family, as well," she raves of motherhood. "But I also know that this is a really challenging year for so many people. It's a challenging year for our country, for our world. And so it's important to be able to be there for friends and family and listen and find silver linings when we can. ... But definitely the birth of my daughter is a big, big moment for me." Of her partnership with Aerie, Katherine says she has "been working with" the brand "for a couple of years now" and has "loved" doing so. "I always love hearing about the projects they're doing and just feel really honored and lucky to be able to be a part of them because they're so aligned with everything I believe in," she tells PEOPLE. "I did a really fun event with them earlier this year, pre-COVID, when my book came out, which was really awesome because they do all these real conversations and real talks that I love being a part of."