ROCKWALL (CBSDFW.COM) - Landon Light has been swimming upstream for much of his life. “You shouldn’t take anything for granted because it can always change,” said the teenager from Heath.

At age 13, Landon earned himself a spot on a swim team in Rockwall. “I didn’t want to swim on the swim team, because I didn’t think I could keep up with everyone else.”

Landon is not being modest. Instead, he’s being honest. CBS 11 first met Landon in October, 2008, when he was diagnosed with Transverse Myelitis.

Dr. Ben Greenberg is Landon’s doctor and says this rare disease causes the immune system to attack the spinal cord. “It’s a condition where the immune system, which is supposed to keep you healthy, gets confused and thinks that your spinal cord is a foreign invader,” explained Dr. Greenberg, who is the director of the Transverse Myelitis Program at UT Southwestern and Children’s Medical Center of Dallas.

Overnight, Landon was paralyzed from the chest down and his doctors feared he might not walk again.

It’s been nearly four years since that gloomy prognosis and somehow, Landon keeps beating the odds. “It’s a great eye-opener that everything is not perfect all the time and that you need God to help you get through everything,” said Landon.

With a combination of treatment, rehabilitation and sheer determination, Landon has steadily graduated from a hospital bed, to a wheelchair, to a walker, and now crutches.

Landon Light of Heath takes a dive. (Photo by Jay Gormley, CBS 11)

Competitive swimming is a continuation of his physical therapy.  Landon still needs help getting up on the starter’s block and he has limited use of his legs in the water.

His swim coach says that hasn’t stopped him from competing against swimmers who are older and have no physical obstacles to overcome. “At the first meet, I cried,” recalled Nicki Ripp, Landon’s coach. “I think everybody in the stands were absolutely blown away,” she added.

Landon continues his treatment at Children’s Medical Center. It’s one of only two hospitals in the nation that specializes in Transverse Myelitis. The other is Johns Hopkins.