Today marks 8 years since my life was transformed by a person I will never meet and never be able to properly thank.

Christmas seemed a long way away in November 2007, when cystic fibrosis had ravaged my lungs to the point that they were all but useless and everyday tasks had become physical feats of the highest magnitude.

Everything changed when we received the call to say that a family somewhere in the UK going through their darkest of times, had consented to their loved one’s wish to become an organ donor.

Over the last eight years I’ve faced tougher battles than I ever thought possible. I’ve had to learn how to breathe again, how to function again. I’ve had to learn how to be “normal” and how to live and plan like someone who isn’t constantly looking over their shoulder. I’ve had to work out what this all means and — at times — that’s taken me to the brink of despair.

And in amongst all that I’ve found a spiritual second home in Hawaii, experienced the overwhelming love of a church-full of people witnessing my marriage, seen two nieces come into the world I would never have met and been able to run around and chase after all of my other nieces and nephews, and watch them grow — some of them all the way into adulthood.

Reflecting on this yesterday in an effort to boil it down into something expressible, I realised everything I’ve learned comes down to three simple things:

1. You will never know how many lives you touch

Consenting to organ donation can save up to seven lives. I have no idea how many lives my donor saved beyond mine, but I can tell you this for sure: they have touched many hundreds more.

My parents lived the first 25 years of my life in the belief that they would outlive me. My brother always thought he would soon be an only child. My wife wondered whether our youngest niece and nephew would even be able to remember who I was.

That’s just four lives before you even start to count the 200 closest family and friends who came to our wedding.

I’m a living legacy for the gift my donor gave, but the ripple effect of that one life still goes on and on with every new person who reads my posts, watches me speak or shakes my hand at an event.

I have no concept of the number of people I’ve manage to reach with my story, but 90% of them would never have heard of me had my transplant never happened.

“I am part of all that I have met.” Alfred Lord Tennyson

My donor is not only a part of me — and me a part of him — but we are both parts of people we have met only for the briefest of periods.

The same is true for you: you touch new lives in new ways every day. Never forget the ripples you send out with every step you take.

2. You are enough

‘Survivor’s guilt’ is a common phrase in transplant circles. Why is it that I should still be here when someone else isn’t?

During the two-and-a-half years I was waiting on the transplant list, growing weaker and weaker, my faith and belief ebbing away with every new infection, I prayed for a transplant every single day.

And every day as I prayed I thought to myself, “I’m praying for someone else to die.”

I recognise now that’s not the case. My donor would have died anyway, regardless of what I did. And if I hadn’t been waiting for a transplant, his organs might have gone to someone else or, worse still, gone unused.

Nothing I did changed either of our fates. But that doesn’t stop be being indebted to my donor and my donor’s family forever.

The problem comes when you realised that it’s a debt that cannot ever be repaid.

And so follows the pressure. The absolute belief that you have to matter. To be someone of substance, of consequence. To live a life of meaning.

All I’ve ever wanted to do is to make my donor proud. To know that somewhere there is someone looking down on me and thinking, “I’m glad it was him.”

But what is ‘a meaningful life’? How can I ever know that I’ve done enough, that I am enough, to justify the gift I’ve been given?

The reality is that none of us can define it, but I’ve finally learned I am enough.

It’s enough to still be here and be living my life every day. It’s enough to be the best husband I can be and support my wife in every way she needs me or wants me to. It’s enough to work for the organisation who saved my life and gave me a chance of seeing a transplant in the first place. It’s enough to be the best uncle I can be, the best son, the best manager, the best employee, the best colleague, the best friend.

I’m not the world’s best at any of those things, but I strive every day to be the very best version of me that I can be. And that’s enough.

Perfection is impossible. All you ever need to be is enough, and you already are.

3. The world is full of joy

Over the course of the last eight years I have — quite genuinely — lost track of the number of friends I’ve lost.

Sam, Jess, Theo, Gareth, Kerry, Jo, Toria, Emily, Anders, Pete, Rob are just the names I could think of off the top of my head without pausing my typing to think it through properly — and it doesn’t even include family members like my deeply-beloved Gramps or my wife’s aunt. I’ve been to more funerals than my parents.

All we see if we look at the news is sadness and sorrow, horror and fear. The world is full of sadness and I’ve experienced more than my fair share over the last eight years and even before that.

But what I’ve come to realise is this: while the world is full of sadness, it contains far, far more joy.

Every single one of the people I’ve lost have given me far more joy than their deaths gave me grief. I’m filled with immeasurable gratitude for knowing each and every one of them. I’m a better man for having known them all.

And joy abounds everywhere. When I was working at World Vision UK, the most remarkable thing that struck me was no matter where we would get stories back from — from Syrian refugee camps to villages devastated by Typhoon Haiyan in the Philippines — there were always be pictures of people laughing.

Most often, it was children. Children are our future and our hope. Their innocence and their willingness to give over completely to feeling joy in all its boundless, manic energy is astonishing. And it’s something we must always cling to.

Before my transplant I worked with young people at Milton Keynes Theatre, assisting in workshops for children as young as four and five. I used to tell people then the reason I loved working with kids.

“The most important thing in a 5-year-old’s life,” I would repeat to anyone who would listen, “Is whatever they are concentrating on right now, this very moment.”

There is no greater joy than the laughter of a child, and no greater goal for any of us to strive for than to remember that sense of wonder, of awe, of complete enjoyment in every single moment of the day.

And we must all take pause when all seems bleak to look around us and see the joy and the happiness that exists in the world, because it’s always there.

These things I’ve learned over eight years of a life that I have no right to be living. But I am living it. And as long as I am I will continue to do whatever I can to be the very best version of me in this very moment.

And for my donor, I now know that’s enough.