Johnny Paradise, 29, is tired after a 450-mile round trip from Limerick to Belfast. But this was no weekend getaway with the lads - Johnny was in Belfast City Hospital for his first annual health check-up since donating one of his kidneys to a stranger.
Two years ago, the financial analyst was at home in the Limerick suburb of Corbally watching an RTE documentary that featured sports pundit Joe Brolly donating a kidney to Shane Finnegan, a Belfast-based PR executive suffering from renal failure whom Brolly barely knew.
Once Johnny discovered that people can enjoy a healthy life with just one functioning kidney, he set about doing the same, so that there would be one less person out there on dialysis. Because there is still no legislation governing altruistic kidney donations in Ireland, Johnny travelled to Belfast for a battery of medical and psychological health tests to see if he was physically and mentally fit to become a live donor.
Two weeks before the three-and-a-half hour surgery, Johnny was told that a perfect match had been found for his kidney; it was a 56-year-old man living in Manchester who had been on dialysis for seven years. He knew little else about the recipient of the kidney, other than that he had a hereditary form of polycystic kidney disease so his three children had been ruled out as donors.
After the surgery, Johnny spent a month off work recovering from the procedure. But not all of his family and friends initially approved of his generous plan.
"Some asked 'what if I need a kidney or you have a family in later life and one of your children needs a kidney?'," he says. "But the vast majority of people spend their lives with two healthy kidneys and I would need to be extremely unlucky if one of my children needed a kidney and their mother wasn't a match.
"If someone is in immense suffering and is facing death, regardless of whether you know them, you should help if you have the ability to do so."
Most people wouldn't think twice about undergoing a serious operation to donate an organ to a loved one but would rule out doing the same for a stranger.
For extreme altruists like Johnny, though, all lives are of equal value. They base their decisions on whether their actions are good for the world, sometimes at the expense of their parents, siblings, spouse or children.
These are also known as do-gooders, at least in a new book called Strangers Drowning: Voyages to the Brink of Moral Extremity by Larissa MacFarquhar, a long-time writer for The New Yorker. It tells the stories of individuals who devote themselves to the lives of strangers and examines what drives them to do it and why we tend to dismiss do-gooders - itself a loaded term - as self-serving, unnatural, or overly earnest.
"In Ireland, the UK and Australia, there is extra annoyance at people who do good," MacFarquhar says.
"Why do we care so much about the qualities that can accompany such people, like self-righteousness? Is it better to be a delightful cynic who never does a thing?"
Many of us need the sight of a stranger suffering before we feel duty-bound to help, like a friend who has been stricken by cancer or the sight of a freezing homeless man on the street.
Others act when confronted by a crisis, like the volunteers who rushed to the shores of the Mediterranean to assist the thousands of refugees arriving by ramshackle boats after seeing photos of the lifeless body of a three-year-old Syrian boy that had washed up on a Turkish beach.
But most of our selfless acts are carried out for our own family and friends, not to ease world poverty. Being doused with water for the ice bucket challenge and sharing the footage on Facebook to raise money for ALS, or running a marathon for charity, may be laudable charitable acts, but we can swiftly return to our normal lives, satisfied that we have done a good deed.
Celebrity philanthropists, like Bono or Bob Geldof, don't count as do-gooders, either, MacFarquhar says. Nor do billionaires who strive to give away their fortunes to good causes, like Chuck Feeney, whose foundation Atlantic Philanthropies recently gave €138.4m to Trinity College Dublin - the largest donation in Irish history - to help fund research into a cure for dementia.
Do-gooders don't need photographs of dead refugees or statistics on crippling diseases to act; they know there are crises everywhere and they seek them out, make them seem like a kind of virtuous ambulance-chaser.
They constantly think about how they can lead as moral a life as possible, such as by living frugally and giving away their earnings to an NGO in Africa, or putting themselves in severe danger to help others.
The subjects in Strangers Drowning include a Methodist minister who allows the homeless to move into her house; a couple who sets up a leprosy colony in the wilderness in India, living in huts with no walls, knowing that their two small children may contract leprosy or be eaten by panthers.
Then there's an American woman who founded a woman's health clinic in the Nicaraguan jungle, and a working-class couple who realise after having two kids and adopting two more that they have a gift for raising children and end up adopting 20 kids over 15 years.
For readers, the most exasperating of all is Aaron Pitkin (not his real name), who tells his girlfriend that he can't wash the dishes because it will detract from his crusade to ease the pain suffered by poultry and other animals.
While writing the book, MacFarquhar was told that these do-gooders must be "mentally ill". She dismisses this but says many of these people have one commonality.
"One theory is that of the 'parentified child', where they grow up with at least one dysfunctional parent, such as an alcoholic, and may feel obliged to fix this, by becoming a perfect student at school, doing the housework, the cooking, and taking care of siblings," she says.
"They may grow up to try to fix the world like they tried to fix their family. I looked at the people I'd written about and the vast majority fall into that category."
Altruism is now a hot topic. Effective altruism, a movement that guides donors to the most effective charities and helps people choose the careers that will do most good.
A TED talk on the subject by Peter Singer, a high-profile moral philosopher and author of The Most Good you Can Do, has been viewed nearly 1.3m times since it first went online in 2013. He's famously argued that it is immoral to buy anything but necessities when your money could be used to save lives.
There are now 1,333 members worldwide of Giving What We Can, an international society dedicated to ending extreme poverty through effective altruism. It was founded in 2009 by Toby Ord, a researcher in moral philosophy at Oxford University who has given away over a third of what he has earned and is on track to donate £1m over his lifetime.
Its members pledge to give 10pc of their income to the charities that are most effective at saving and improving lives.
The concept of "earn to give" is popular among some sections of the community and some members will retrain as a software engineer or an investment banker so they can earn as much money as possible and then give it away.
Michael Nee, 30, founded the Dublin chapter of Giving What We Can with his girlfriend Emily Bourke, 27, a PhD researcher at Trinity. Both volunteer with charities in their spare time but agreed they should do more after reading about Singer and Ord. Their meetings in Dublin attract between eight and 20 people a month.
Michael donates 10pc of his income, but because Emily's doing a PhD and her income is irregular, she gives anywhere between 5pc and 10pc of her earnings.
Emily says: "After reading about all of this, it becomes hard to argue against the concept that all lives are of equal value and that, considering the wealthy nature of the West, the money you have can go very far elsewhere. I thought if I agreed with this stuff, that I'd start feeling like a hypocrite if I wasn't doing it.
"It doesn't feel like a guilt thing for me, or like a chore. We all think we would like the world to be a better place, and this is a step I can take to help that happen."
The pair have had to make minor adjustments to their lifestyle because of their new financial commitments. They don't eat out as often, have friends over instead of going to the pub, and don't go on holiday as frequently.
"There is a danger of going down that hole where you think about the impact a cup of coffee you had would mean less money to de-worm a child, but if you get into that cycle you are not going to be able to continue donating," Emily says.
"I buy fewer coffees since I've been thinking about this, but I do enjoy my life."