Every Sunday, Michael Jackson went up to a room over the garage. His mother finally explained what he did there.

Lots of houses have a room over the garage that ends up as storage. Boxes, old bikes, the Christmas decorations nobody wants to haul down.

At the Jackson house, that room had a very different job.

Katherine Jackson is Michael’s mother, the woman who raised him and his eight brothers and sisters. In a 2010 interview with Dateline NBC, for a special called “Michael Jackson: A Mother’s Story,” she opened up about a habit Michael kept at home, one she saw happen under her own roof every single week. And it all happened in that room upstairs.

The family lived in Encino, California, back then. Michael called that house home from 1971 until 1988, from the time he was a boy in the Jackson 5 until long after he’d gone solo. He once gave a tour of the place on camera, so you can get a feel for the home where this story took place.

Michael giving a tour of the family home in Encino

Katherine started her answer with, “Every Sunday he would go upstairs in our…” and then she stopped and backed up to explain the room itself.

Here’s what she said.

“…we have another room up over the garage, and he made it into a little studio for dancing and exercising, and he would go up there and dance for two hours straight without stopping.”

Two hours straight, every Sunday.

If you’ve ever tried to keep dancing through a few songs at a wedding, you know how long two hours really is. Most of us would be sitting down by the second song.

So what was it all for? Katherine had a simple answer. “So he wanted to be ready for his 2 hour concert.”

Think about that for a second. A song on a TV show is over in a few minutes, but a concert asks a dancer to keep going all night. Michael wanted his body ready to go the whole distance, so every Sunday he went upstairs and did the full two hours.

We don’t have film of those Sunday sessions. You can still watch Michael working through a dance rehearsal, though, and see how much effort went into moves that looked so easy on stage.

Michael working through a dance rehearsal

NBC’s report says the choreography Michael showed in “Thriller” took hours of practice at home, and you can see where those hours went in the famous zombie dance.

Michael and the “Thriller” dance

NBC also pointed to one more night where all that practice may have paid off most of all. That was “Motown 25,” the 1983 TV special where Michael performed “Billie Jean.”

Katherine didn’t need a long speech to sum it up. After describing the room and those Sundays, she said just five words.

“And so it paid off.”

That’s a mother talking. She knew exactly where her son was every Sunday, and she got to see what all those hours upstairs turned into once he stepped on a stage.