NATCHEZ, MISSISSIPPI. It's mid-December on the Mississippi set of "Get On Up" and it's possible that the hardest working man in show business is the young actor playing The Hardest Working Man in Show Business.

We're between shots in a scene recreating James Brown and The Famous Flames' iconic performance in the concert film "T.A.M.I. Show" and everything is resetting. 

For Chadwick Boseman, though, there's no such thing as a reset. The cameras may not be rolling, but Boseman's feet keep shuffling across the shiny green linoleum of the Natchez Auditorium stage, which is standing in for the Santa Monica Civic Auditorium. He only pauses to run over to the monitor to see how his footwork looks, but then he returns to the stage, dancing his way there and back.

Chadwick Boseman has become something of a perpetual motion machine, but if you watch old videos of James Brown, the rhythmic restlessness is one of the first things you'll notice about the Godfather of Soul as well. 

When I mention this to the movie's choreographer Aakomon Jones, also playing one of the Flames, he's instantly gratified.

"That's literally where I start," Jones smiles. "Because we got into the cool slides and all that footwork and the spins and all that. It's just this thing that James Brown does when he's like driving the beat, he's clicking both heels, one into the other -- right-left, right-left, right-left. I worked with Chad on that for hours, maybe two days straight before we ever started trying to add flashes. I knew that if he got that, he had 60 percent of what James Brown is as a performer as far as quantity, because he does that throughout his entire performance. He'll flash here, he'll slip off to the fight and dance-break and he'll hit a spin or a split, but 75 percent of the time? He's right-left with the heels. That's what keeps the band locked in."

And Boseman is certainly locked in as well. 

Director Tate Taylor, the man behind the Oscar-winning hit "The Help," is shooting James Brown's "T.A.M.I. Show" numbers as full, uninterrupted songs. [After editing, I highly doubt that's the approach Taylor will take, but I can assure you that at least in the moment, the performances are sustained.]

Boseman goes through the entirety of his "Out of Sight" performance, which includes spins, a split and ends with him on his knees as the crowd shrieks.

"Mr. Brown, would you like another?" Taylor asks. And every time, Boseman does, indeed, want another.. 

Backed by a seven-piece brass band, as well as three guitarists, to say nothing of the Famous Flames, Boseman isn't the only one keeping busy between takes, but he just seems to be keeping busier. One particular move involves a spin and then a microphone tilt-and-catch and it's causing problems. Over and over, Boseman pushes the microphone out, spins, catches the mic and goes into a kneel. Actually, as he copies the motion over and over again, it doesn't appear to be causing problems, but you can sense that Boseman worries it might become tougher when he has music and wailing vying for his attention. Each of the repetitions is perfect, but he's cultivating muscle memory. He only pauses when assistants rush out on-stage to brush off James Brown's pants.

Boseman's enthusiasm and energy are unflagging as the morning goes into early afternoon. 

"Well the secret is, it ain’t no secret," Boseman says of keeping juiced. "We had a lot of rehearsals. We had a lot of, just stamina like in dance rehearsals doing stuff over and over and over again. Doing different numbers and doing all the numbers in one day. All that stuff is like you’re building up a stamina so that you can do it on the day, we’ve got to do it take after take after take. So that’s what it is."

It's only a few hours later, darkness fallen and the long shooting day complete, that Boseman is able to sit for questions with a pair of reporters. He hasn't exactly collapsed, but he's slumped in one chair and won't move except for to rotate into a different seat.

Asked about maintaining that level of motion for that long, Boseman quickly interjects.

"Exhausting," he says.

But he doesn't "say" it so much as "croak" in a thick Southern drawl.

"[P]art of it is you don’t want your energy to get down so you want to stay up as if you were gonna do his whole show," he explains. "That’s my philosophy. And the other thing is, you know, we’re shooting 14, 12... Have we gone 14? We haven’t done that have we? But we’re shooting long hours every day and you don’t have the time to practice like you did when you wasn’t shooting. So I know that next week we’ve got to do three days of music and dance. So I’ve got to stay in shape for what’s coming. So it’s a matter of just being diligent about the fact that I have to keep my wind up and my legs up and stamina up because it’s not. You don’t just start doing the Mashed Potato like he does the Mashed Potato or any of those dances at that, it’s a set way that it’s done and his body’s moving in different directions. And you can’t just stop doing it."

Talking with the actor in his trailer as the hair and makeup team divest him of wig and prosthetics, you can sense that this nightly ritual is more than just superficially transformative. As the external pieces of James Brown are removed, Boseman's voice shifts. Like Brown, Boseman was born in South Carolina and there's a thick growl to his accent when we initially enter his trailer, but it becomes smoother and smoother as he eases out. Helping the process is the scalp massage he's receiving after the day's wig is removed, but perhaps fearing he might slip too far from character, Boseman insists on listening to James Brown in the background.

"It’s different depending upon which age we’re playing," Boseman says of the preparatory process. "If it’s the older James Brown he takes a little longer to get ready in the morning. I think we got it down to what? Two-and-a-half hours. And it started at like three-something. So it’s down to two-and-a-half hours. They work really quick. They’ve got it down to where everybody eats at a certain time, different parts and then we start again. For the young James Brown it’s like – I mean it’s probably like an hour, right? I think it’s like an hour."

For better and sometimes for worse, James Brown was a force of nature and you'd think it was difficult casting the role. Taylor, however, demurs. 

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A long-time member of the TCA Board and a longer-time blogger of "American Idol," Dan Fienberg writes about TV, except for when he writes about movies or sometimes writes about the Red Sox. But never music. He would sound stupid talking about music.