Around this time every year, I start hearing from friends who tell me they just saw one of our St. Jude Children’s Research Hospital Thanks & Giving spots on TV. Or on an airplane. Or in a movie theater. Or on billboards and about a zillion banner ads on the Internet. And they ask me about my bond with the hospital, which my father founded 46 years ago.

Click here for photos of Danny Thomas and Marlo Thomas and more at St. Jude Children’s Research Hospital.

In our house we weren’t allowed to take phone calls during dinner; but my father was allowed to break that rule if a call came in from St. Jude. And I’ll never forget when he came back to the table, he’d sometimes have tears in his eyes, because a little boy named David “didn’t make it.” Or he’d be beaming, because a little girl named Amy was “going home at last.”

My sister and brother and I would always wonder: Who are these children? And why are they so important to our Daddy? It wasn’t till after my father was gone that I think we really understood his passion for the children and their parents.

For me, that came when I visited St. Jude a few months after he died. Because this would be my first visit since his death, I was afraid to go inside, afraid of being overcome by the wave of memories of all the times I’d been there with him. I just sat in my car in the driveway and cried.

Finally, I pulled myself together, and when I walked into the hospital, I saw a party going on. Kids in paper hats. Ice cream and cake on the table. Balloons everywhere. Lots of happy noise.

I asked a nurse, “Whose birthday is it?”

She said, “Oh, it’s not a birthday party. It’s an off-chemo party.”

Here were all these little kids celebrating and deriving strength from another child’s turn for the better. And all the parents had tears in their eyes. If this child had made it, they thought, maybe their beloved child would, too. That was the moment I understood.

My sister and brother had their own epiphanies, and though we had always “helped out” with St. Jude over the years, in 2004 we began to think about conceiving a national program that could raise millions of dollars. We didn’t want to just raise funds with our program, but raise awareness, too. So that moms and dads and grandparents of sick kids would know that there was a place to turn when no other place knew what to do.

We wanted our program to take place at a time when families are together, so we chose Thanksgiving. Each year St. Jude launches its annual “Thanks & Giving” fund-raising campaign. This is our fifth year! It’s a very exciting campaign, an unprecedented coming together of some of the country’s most famous brands and companies, media and celebrities, in which we ask holiday shoppers to “Give thanks for the healthy children in your life, and give to those who are not.”