HE had a death sentence hanging over him for many years but Donal didn't sit around feeling sorry for himself.
Instead he used the time he had left to make an impassioned appeal to other teenagers to grab life with both hands.
He knew how precious life was and he wanted those who had been given the gift of life and good health to choose to live every day to the fullest and not to see suicide as a way out from life's difficulties.
As he faced down his inevitable death the teenager spoke with a maturity and a calmness that has never been seen so publicly before.
"If I'm meant to be a symbol for people to appreciate life, then I'll be happy to die," he said.
He was diagnosed with cancer when he was just 12 and despite battling it bravely for many years, he finally succumbed to the illness last night.
The eloquent teen, from Blennerville, Co Kerry, touched the hearts of the nation when he decided to go public about his battle with the illness.
In a heartbreaking interview with the 'Sunday Independent' just last month, he spoke of his dream to play rugby for Munster.
"I wanted to live, to play for Munster, to travel the world, to raise children and die when I'm 100, not 12," the teenager said.
He spoke movingly about how his life had changed after he was diagnosed with cancer in September 2008.
"I knew it was bad but I didn't understand the severity of it.
"I had cancer, a tumour that had grown on my right femur just above my knee and little did I know it would destroy parts of my life that I had never planned on letting go of," he added.
But in the time he had left he still managed to raise more than €50,000 for Old Lady's Hospital for Sick Children in Dublin while he was a patient there.
He adored coaching underage players at Tralee Rugby Club after he could no longer play due to his illness.
Although he was unquestionably a brave young man, Donal was philosophical about his condition.
Even Munster rugby hero Paul O'Connell was in awe of Donal's inner strength.
Donal had also been in contact with Alan Quinlan and had become friendly with Munster talisman O'Connell, as well as Leinster's Shane Jennings.
"It's hard to relate to some young guys, but whatever journey he's been on, he's quite mature and very easy to relate to," O'Connell previously said in an interview.
"Even when I was injured I used to enjoy shooting the breeze with him because he'd give me a massive lift."
Donal highlighted his anti-suicide message right up to the end.