"I just want to get the most out of these arms, and just as goals come up, knock them down and take it absolutely as far as I can," Brendan Marrocco said Tuesday.
The 26-year-old New Yorker spoke at a news conference at Johns Hopkins Hospital, where he was joined by surgeons who performed the operation.
After he was wounded, Marrocco said, he felt fine using prosthetic legs, but he hated not having arms.
"You talk with your hands, you do everything with your hands, basically, and when you don't have that, you're kind of lost for a while," he said.
Marrocco said his chief desire is to drive the black Dodge Charger that's been sitting in his garage for three years.
"I used to love to drive," he said. "I'm really looking forward to just getting back to that, and just becoming an athlete again."
Although he doesn't expect to excel at soccer, his favorite sport, Marrocco said he'd like to swim and compete in a marathon using a handcycle.
Marrocco joked that military service members sometimes regard themselves as poorly paid professional athletes. His good humor and optimism are among the qualities doctors cited as signs he will recover much of his arm and hand use in two to three years.
"He's a young man with a tremendous amount of hope, and he's stubborn - stubborn in a good way," said Dr. Jaimie Shores, the hospital's clinical director of hand transplantation. "I think the sky's the limit."
Shores said Marrocco has already been trying to use his hands, although he lacks feeling in the fingers, and he's eager to do more as the slow-growing nerves and muscles mend.
"I suspect that he will be using his hands for just about everything as we let him start trying to do more and more. Right now, we're the ones really kind of holding him back at this point," Shores said.
The procedure was only the seventh double-hand or double-arm transplant ever done in the United States.
The infantryman was injured by a roadside bomb in 2009. He is the first soldier to survive losing all four limbs in the Iraq War.
Marrocco also received bone marrow from the same donor to minimize the medicine needed to prevent rejection. He said he didn't know much about the donor but "I'm humbled by their gift."
The 13-hour operation on Dec. 18 was led by Dr. W.P. Andrew Lee, plastic surgery chief at Hopkins.
Marrocco was being released from the hospital Tuesday but will receive intensive therapy for two years at Hopkins and then at Walter Reed National Military Medical Center in Bethesda.
After a major surgery, human nerves regenerate at a rate of an inch per month, Lee said.
"The progress will be slow, but the outcome will be rewarding," he added.
Associated Press Writer David Dishneau contributed to this story from Hagerstown, Md.