Two-year-old Elliott Livingstone has just left the London hospital where he's spent half his life.
The toddler suffers from the heart disease dilated cardiomyopathy, which caused his left ventricle to weaken and enlarge and meant his heart wasn't able to pump blood effectively.
"Our cardiologist said the heart works as though it's running a marathon for every minute of every day," Elliott's parents Candace and Adrian Livingstone wrote on a Facebook page documenting their son's journey.
Just before Christmas in 2014 Elliott suffered a complete heart block and was fitted with a Berlin Heart, which pumps blood from the outside the body.
(Elliott’s Heart Transplant Journey /Facebook)
After 14 months at Great Ormond Street Hospital, Elliott received a donor heart in a seven-hour operation.
"If it wasn't for a parent choosing to give life in their darkest moment, Elliott wouldn't be here," his parents wrote.
On April 29, the two-year-old walked out of hospital, wearing a blue Superman jumper and with a Thomas the Tank Engine suitcase in tow.
"The moment we have fought so hard for is finally happening. Tears were shed. A million thank-yous uttered," his parents posted on Facebook.
The family is now looking forward to an ordinary life.
"We don't want anything fancy. Mundane and normal will do us just fine. As long as Elliott is happy, we will be content with what we have," his parents wrote.
Mr Livingstone is now taking part in a run to raise money for Great Ormond Street Hospital.