What makes that remarkable is that Declan had a double lung transplant 10 years ago.
The Offaly man has been training hard for the 6th European Transplant and Dialysis Games that get under way in Dublin next Sunday.
Declan, a native of Geashill, Co Offaly, now living in Loughrea, Co Galway, will be one of 350 athletes from 24 countries taking part in the games.
He has taken part in previous world transplant games in France and Japan but this year will be the only double lung transplant patient.
Declan, who lives with his partner Carmel Clarke and children, will be taking part in the 5km run as well as the ball throwing.
He is hoping to run the course in less than 30 minutes.
Declan never played sports before he got his two new lungs and is anxious to let people know how much his life has improved.
The youngest of a family of two brothers and three sisters, Declan is the only member with cystic fibrosis.
He was seriously ill before he underwent the double lung transplant in the Freeman Hospital in Newcastle.
“I was fine when I was younger but when I got to my late teens I began to get sick. I got worse in my early 20s,” he recalled.
Declan did not realise just how ill he had become until he was told he needed a transplant.
“I was never fit enough to get involved in sports and I used to watch the lads playing football and wishing I could join them.”
Declan now enjoys what most people take for granted – living a full and healthy life. “I can do what I want, go where I want because I no longer have any restrictions and it’s fantastic.”
His mother, who maintained a bedside vigil during the six weeks he was recovering from his transplant, described his recovery as miraculous.
Before the transplant Declan was on 10 litres of oxygen 24 hours a day and had a BiPAP machine to help him breathe.
His partner, who is a member of Loughrea Athletics Club, got him interested in running and they often trained together.
Declan did not need much persuading to put on his running shoes.
“I just love the outdoors and get out whenever I can,” he said.
And he is always keen to make people aware of the issues around having cystic fibrosis.
“Of course, I want to win a medal next weekend but I what I want even more is to make people more aware about organ donation,” he said.
“I am passionate about organ awareness because I have seen friends who have become ill because of organ failure and I have been given a new lease on life because of organ donation,” he said.
* For organ donor cards free text DONOR to 50050 or contact the Irish Kidney Association at 1890 543639. The website address is www.ika.ie.