James Van Der Beek revealed on November 3 that he was diagnosed with stage 3 colorectal cancer at the age of 46. Today, the actor is opening up about his health journey in hopes of raising awareness about a disease that’s becoming increasingly common among otherwise healthy adults under 55. .

“That’s one of the reasons why I want to talk about it and THE “why I talk about it so openly,” Van Der Beek, 47, tells PEOPLE in this week’s cover story.

“I’ve been dealing with this in secret for a while, and in the past I’ve found it helpful and cathartic to share things publicly,” said the actor, who lives on a ranch in Texas with her husband. wife Kimberly, 42 years old, and their six children, Olivia, 14 years old, Joshua, 12 years old, Annabel, 10 years old, Emilia, 8 years old, Gwen, 6 years old and Jeremiah, 3 years old.

“And I found a lot of support that way. But more than that, I really wanted to raise awareness.”

According to the American Cancer Society, 1 in 5 new colorectal cancer diagnoses are in people under age 55, up from 1 in 10 in 1995.

Van Der Beek says he had no reason to suspect he would face such a frightening diagnosis at this point in his life. He had no family history of cancer and took care of his body through exercise and nutrition.

“I have always associated cancer with age and an unhealthy, sedentary lifestyle. But I was in incredible cardiovascular shape. I tried to eat healthy – at least from what I knew at the time.”

But in the summer of 2023, he noticed changes in his stools. He thought it was his diet that was to blame.

“I thought maybe I should quit coffee,” he says. “Or maybe don’t put cream in the coffee.” But when I deleted that and it didn’t get any better, I thought, “Okay, I better get that checked out.” »

Following his colonoscopy, he was not worried. “I felt really good coming out of the anesthesia, that I had finally made it,” he says. “Then the gastroenterologist said – in the nicest bedside manner – that it was cancer. I think I was in shock.

Van Der Beek immersed himself in treatments, which typically include surgery and chemotherapy. And while he doesn’t want to share specific details about his medical regimen just yet, he says, “If you’ve heard of it, I’ve probably talked about it.” »

“It’s a crash course in mastering the mind, body and spirit,” he explains. “I said to myself: either this will take me out of the body, or it will teach me to really live in it.”

Although he tries to stay positive, he admits it can be difficult at times.

“The tricky thing is that there are so many unknowns when it comes to cancer,” he says. “You think, ‘How can I solve this problem?’ Does this cure me? Does it hurt me? Does it work? Is it coming back? For someone who likes answers, not knowing is one of the hardest things. »

As for his current state of health, he does not want to talk about stages of healing or remission. But he says he feels good.

“I am cautiously optimistic. I am in a healing place, my energy levels are great. When I’m completely out of the woods for what seems like a responsible period of time, I’ll come back and let you know.

He adds: “I have a lot to live for.”

To read more about James Van Der Beek’s cancer journey, pick up the latest issue of PEOPLE on newsstands Monday