R.J. Cooper returns to the kitchen full-time on Tuesday at Rogue 24, where he plans to debut a whole new menu. (Tim Carman/The Washington Post)

R.J. Cooper’s doctors earlier gave him the green light to return to work full-time following open-heart surgery in January. Cooper says, in some ways, he’s feeling better than ever following surgery to repair a heart defect known as hypertrophic cardiomyopathy, or a thickening of the heart muscle that makes it harder to pump blood. His ticker, for starters, is no longer working at 30 or 40 percent of capacity, he says.

The main thing, Cooper says, is that he has to train his body all over again to withstand the rigors of daily restaurant life, even though he’s been back in the kitchen, off and on, for a few weeks. The way the chef explains it, it’s not unlike an athlete — well, an athlete who likely has a pot belly — who has to condition his/her body to run a marathon.

“The only thing I don’t have is my stamina,” says Cooper, who notes that he’s refraining from the chef’s typical one-two punch (coffee and Red Bull) to push his body. “It’s trying to keep your legs. I can walk, but I can’t run yet.”

Cooper was pleased with the way Rogue Sessions turned out — and not just because it kept his restaurant full (or semi-full) while he was recovering from surgery. The multi-week Sessions featured guest chefs, who assumed control of Cooper’s kitchen for a week, mixing some of Rogue 24’s signature dishes with their own takes on modernist cooking.

The chefs included not only Fukushima but also Scott Drewno of The Source, Spike Gjerde of Woodberry Kitchen in Baltimore, Bryan Voltaggio of Volt in Frederick and former “Top Chef” contestant Jennifer Carroll, among others.

Together, according to a publicist, the chefs prepared some 32,000 dinners dishes (*) and raised more than $10,000 for Share Our Strength .

“We didn’t do it as a publicity stunt to stay open. I wanted to do Rogue Sessions, anyway,” says Cooper, who originally conceived the idea of them as a series of monthly guest chef appearances. “It’s difficult to kind of monitor whether it kept us afloat. We’ve been doing well since we opened.”

Cooper plans to keep the momentum going with a revamped menu, in which he replaces virtually all 24 courses. Among the debuting dishes is Cooper’s take on a gyro, in which he wraps lamb tartare in mini butter lettuce leaves, as well as a plate or two that incorporates Oreos, in a nod to the cookie’s 100th anniversary.

As he assumes control of his kitchen again, I wondered whether Cooper had any epiphanies while he went under the knife — or after. Anything that might shed some light on the new and improved R.J. Cooper.

“Life is too short,” he answers. “You can’t say you’re going to do something and not do it. You’ve got to go out and do it.”

* The publicist had originally noted 32,000 dinners, but when contacted again, she clarified that it was 32,000 dishes served during Rogue Sessions.