Driven to succeed.

Marshall Cohen is back kicking dirt at clients' construction sites. Only a year ago he had been on his way to a wheel chair.

Born with a deformed leg, Cohen, 64, refused the sedentary life of many real estate lawyers.

"I was taught by a client, one of New York's premier owner-managers of commercial properties, you can't do even the simplest transaction unless you visit the site and understand the physical realities underlying the paperwork," Cohen says.

But not long ago Cohen, ah avid tennis player, faced a tough choice: continue living with the deformed leg and end up in a wheel chair or replace the leg with a new high tech prosthetic limb, a complicated process fraught with risks.

Undeterred by childhood operations, physical therapy and orthopedic shoes, Cohen had earned a Ph.D. and then a law degree. He joined Fried Frank, moved to a partnership at Tenzer Greenblatt, a real estate law firm, and became a managing partner at the New York Firm of Stadtmauer Bailkin, putting in 12-hour days in the practice of government incentives and real estate transactional law. Six years ago Cohen's life changed. He developed sciatica, a debilitating spinal condition caused by stress from his deformity. Cohen stopped tennis and took up acupuncture. Doctors told him if he didn't watch out he could end up in a wheel chair relatively soon.

Cohen had heard about new developments in prosthetic legs. But they came with a high risk. There was no guarantee the prosthetic limb would succeed and he could end up in the wheel chair sooner than expected. For this reason, no orthopedist was willing to amputate.

Early last year, Cohen met Dr. Joseph Lane.

"I told him I am 63 and trying to figure out how to live the next 20 years," Cohen recalls. When Dr. Lane suggested amputation, Cohen started to weep. "Where have you been all this time?" he asked.

Dr. Lane warned Cohen of the risks and advised him to meet with Eric Schaffer, a 38-year old Hicksville, Long Island prosthetist, an expert in designing state-of-the-art artificial limbs.

Schaffer examined Cohen's leg. "He was disappointed," Cohen recalls. "He said it wasn't the biggest leg he'd ever dealt with. He wasn't going to break any records here."

Schaffer told Cohen he would build him a $75,000 limb with a computerized knee that reads sensors in the foot 50 times a second and moves with a gait. Cohen would have to plug in the leg every night and charge it up.

Schaffer introduced Cohen to David McGill, his in-house lawyer, an amputee who had one of Schaffer's bionic legs.

"Now," said Schaffer to Cohen, "what would you like to do?" Cohen said he'd like to think about it. His wife, Jeanne Keh, registered nurse and former spouse of the late restaurateur David K, was all for it. But Louis Perfetto, his younger law partner, was skeptical. So Dr. Lane introduced the two to Paddy Rossbach, an amputee and internationally award-winning horsewoman who is president of the Amputee Coalition of America. The three had a two-and-a-half-hour conversation in Cohen's of rice. Perfetto was sold.

Cohen then invited his brother Jerry to join him at a convention of the Amputee Coalition and the two studied the process and observed people with computer legs, a.k.a. C legs. Cohen decided to go through with the operation and set a date with Dr. Lane for August, 2003.

To prepare, Cohen continued to study C leg users and trained for four months with David Balsley, an amputee specialist. He learned new muscular control and increased cardio vascular endurance by swimming a half-mile and riding a stationary bike four miles each day.

At last, Cohen was ready, but the blackout struck the week of his scheduled operation, so he underwent the operation a month later on September 11, 2003. In another month, the limb was ready for use.

"It took me a few weeks to get used to, but now I'm more mobile than before," Cohen says. "I'm walking further than 1 have in the past and I've started playing tennis again."

He's now looking for a friendly game of doubles at Tennisport in Long Island City. Cohen is also back to his rigorous work schedule. He rises early, goes through strenuous exercises and whizzes around New York to his office or to meet with clients.

Recently Cohen and Perfetto inspected a development site on the south shore of Staten Island, where a client is developing 16 row houses. Cohen walked around 7,500 s/f of raw office space where another client is expanding in lower Manhattan. He has returned several times to 38th Street and Sixth Avenue to discuss and explore a complex retail development on several floors.

To get to the sites, Cohen drives an SUV, equipped with sophisticated speaker systems for telephoning and a laptop computer.

"Thanks to the disability laws, I can park almost anywhere," he says. "When it comes to driving, the disabled have more privileges than diplomats and journalists. 'No Parking Any Time' is my favorite sign."