Let's get this out of the way first. The subject matter of HBO's documentary One Last Hug is heartbreaking, and you're going to cry when you watch it. You might even question why you'd put yourself through it. Your brain will try to find reasons not to watch. You'll think, "Why, with so many entertainment choices at my fingertips, have I chosen to invest my valuable time on a topic that makes me ache?"

Kids losing parents. Kids losing siblings. Kids losing best friends.

To natural causes. To war. To murder. To suicide.

It's brutal, and it happens all the time.

One in seven American children under the age of 20 will experience the death of a loved one.

But you'll keep watching.

You'll keep watching despite the fact that it'll dawn on you early in the documentary that there can't be a Hollywood happy ending to these stories because the kids' loved ones will still be gone at the end of the film. When that hits you it's a punch in the gut and you might want to turn it off again ... but you won't.

Because these kids, they can't turn it off. They can't just decide to stop grieving. And as you watch the documentary, the courage they show in facing their grief will grab you. It'll grip you. It'll make you vow to hold your parents or your siblings or your kids just a little bit longer next time you hug. It'll remind you just how fleeting and unfair life can be.

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The documentary, which premieres Monday at 8 p.m. ET/PT, takes place at Our House of Grief Support Center, one of the free bereavement camps that is part of The Moyer Foundation's Camp Erin Network.

The "Moyer" in the Moyer Foundation is none other than long-time MLB pitcher Jamie Moyer. Moyer pitched for eight MLB teams, made an All-Star Game and finished in the top ten in Cy Young voting three times. He racked up 269 wins, but none was close to being as important as the victories he has been a part of at Camp Erin.

"The name Erin came from a girl my wife and I befriended who eventually passed away," Moyer says. "Erin taught us about life. She taught us a lot about grief."

Moyer met Erin through the Make-A-Wish foundation and they sponsored the first camp session in her honor in 2002. That year they had 42 campers attend their lone session. By 2013, Camp Erin had grown to 41 different sessions with more than 2,600 campers attending.

"My parents' generation really didn't talk about these kinds of things," Moyer says. "When I was a young kid, if people passed away you went to a funeral home, paid respects, spent time with family members, people talked about the person who passed away and that was it. Then you came home and put it in the closet and didn't really talk about it. For those who have strong emotional feelings that grief builds up."

Moyer points out that when children are dealing with a loss of the magnitude of a mom or dad or brother or sister, they have nowhere to go once they return to their real lives. In school they feel like outsiders because they've lost someone. They think they're different. Sometimes they fall out of friendships that they used to have or they lose interest in the things they enjoy. Grief can become overwhelming.

"Every child at the camp has lost somebody," Moyer says. "It opens their eyes to the fact that they aren't the only one. There are several thousand kids, even millions, in the same situation. The camps allow them to let out their thoughts and feelings in a safe environment. The strength of these kids and what they're willing to share is amazing. They come to the camp as strangers but there are so many people caring and sharing and loving that it helps them deal with loss."

There are no barriers to entry, as camps are free and run by volunteers and professional counsellors.

"If you're able to witness a camp, it can change your life," Moyer says. "It has changed so many lives. It's really heartwarming for us and it's very humbling to be able to create a camp like this. We have military children at the camps and we had kids from the Newtown, Connecticut, shootings. The stories these kids have can boggle your mind."

Moyer's oldest daughter, who is now a freshman in college, attended a camp and made such a strong connection with one of the children there that she cried when it was time to leave.

And that's the power of One Last Hug. Every kid reminds you of a kid you know, or your own kids, or yourself as a kid. You have to watch because once you meet the kids who were brave enough to bare their souls to you through the documentary, you want to make sure that they're going to be OK. Just like Moyer's daughter, you won't want to leave.

-- Jon Finkel is the author of The Dadvantage: Stay In Shape On No Sleep With No Time And No Equipment. Follow him on Twitter @Jon_Finkel.

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