As King Charles III and Queen Camilla arrived at St. George’s Chapel at Windsor Castle for Easter Sunday service, Princess Kate and her family were notably absent. Days prior, the 42-year-old royal had announced that she’s been diagnosed with cancer, sending shock waves around the world. “Part of her day-to-day routine is trying to get her strength back,” a source exclusively tells Life & Style. “She’s going through her treatments, which include chemotherapy, so she’s not supposed to push herself too much.” It’s taken some getting used to for the mother of three. “Kate’s anxious to get back to juggling royal duties and the children, but that will take some time,” the source admits. “Thankfully, she has the love and support of her family.” Prince William, 41, has been by Kate’s side as much as possible, says the source, taking calls from well-wishers on her behalf and seeing visitors when she’s not up to it. “He’s been such a pillar of strength,” the source says. Kate’s mom, Carole Middleton, has stepped up, too, adds the source, making sure Prince George, 10, Princess Charlotte, 8, and Prince Louis, 5, don’t miss a beat when it comes to things like their schoolwork. “Kate is so grateful to everyone, including her loyal staff, for pitching in.”