ER actress Maura Tierney was diagnosed with breast cancer in 2009, and now she's speaking out about her once private battle with the disease -- including the shocking moment she learned of her diagnosis.
"I remember thinking, 'I'm so young, this can't be happening,'" she tells People. "It was an odd moment."
Tierney is now finished with treatment, which included undergoing a mastectomy and three months of regular chemotherapy.
"It's not fun. You don't feel well," Tierney says about the grueling process. "[But] "if you take care of yourself and exercise, it helps. Exercising is extremely important."
Next up for Tierney is a guest-starring role on The Good Wife this fall. She's also now the spokeswoman for Amgen's Chemotherapy: Myths or Facts campaign, where she's sharing her own experience with cancer and is encouraging patients to speak openly with their doctors to fully understand their treatment.