Greg Galeazzi is putting on a white coat at Harvard Medical School six years after losing his legs while serving in the Army.

Galeazzi told ABC News he lost his legs and much of his right arm when a roadside bomb exploded in Afghanistan in May 2011, just one month before he was scheduled to head home.

“It felt like I was an empty coke can on train tracks getting hit by a freight train moving at 100 miles per hour,” said Galeazzi. “All I could do was scream. It’s hard to put into words that sickening, nauseating feeling to see that my legs were just gone.”

“I put my head back and just thought, ‘I’m dead.'”

He blacked out, and when he came to minutes later, he learned his fellow soldiers had applied tourniquets to his arm and legs to stop the bleeding. A Medivac helicopter arrived minutes later to take him to the trauma bay.

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He underwent more than 50 surgeries and physical therapy and now relies on a wheelchair to get around. Despite the life-changing accident, Galeazzi never gave up on his dream of becoming a doctor.

“Not only did I still want to practice medicine, but it strengthened my resolve to do it,” said Galeazzi.

He took 18 pre-med classes and earned his target score on the MCAT. He’s now one of 165 students in his class at Harvard Medical School. He hasn’t decided what kind of medicine he’ll be practicing yet, but he told ABC News he’s leaning toward primary care, to be the first line of defense for patients.

He and his fiancée, Jazmine Romero, plan to tie the knot next year.

He has this advice for anyone facing adversity in their life: “Be patient with difficult times, and even when things may be getting worse for a little while, just be patient and stick it out. Because with time, things do get better.”