It's hard enough battling all your life with a complex heart problem, but imagine facing it with school bullying, bitter custody battles and a step-father you fear.
Shaun Miller experienced all this in his short 17-year life - and rose above it.
When it was clear his body was rejecting his second transplanted heart, the teenager recorded a deeply moving video (pictured) from his hospital bed.
He had trouble posting the video to Facebook for his friends, so instead it remained public on YouTube and went viral overnight, eventually touching the lives of milions of people across the globe.
Before he died, Shaun penned a short book called 'An Awesome Ride'.
Now extra chapters have been added, telling the story behind the story and republished as 'An Awesome Ride: Through a Father's Eyes' (Penguin Random House).
We caught up with dad Cameron Miller about Shaun, an experience at death's door when he was 8, making the most of life - and even meeting Chopper Read...
Here is the message Shaun posted on YouTube, four weeks before hius death in 2012...
And on Dr Phil August 2018 ...
After Shaun died Cameron was given a box of his items - and little meaningful support.
His life then spiraled out of control.
Cameron now wants to help other bereaved parents through the Shaun Miller Foundation, which is fundraising for ongoing support services... https://www.theshaunmillerfoundation.org/
Cameron Miller meeting Mark 'Chopper' Read (below), who he got to know via a homeless man Shaun invited to stay at their home.
Shaun also had a cameo on Neighbours (below)
Shaun's funeral in 2012