A little while ago, I was sitting in a cafe, reading, when an elderly lady approached me. “Excuse me,” she asked. “Would you be able to help me with my shopping?”

I beamed. Of course I would be able to help her with her shopping! Let’s get this shopping-helping show on the road, I wanted to shout. For I am an excellent person and enthusiastic assistant to those in need. Unfortunately, it turned out she didn’t mean shopping as a metonym for shopping bags, but shopping as in the verb. She had not yet been to the shop. This was not me lifting two Lidl bags and carrying them to the bus stop, as I had envisioned; this was me going to Lidl.

Forty-five minutes later, this wily elder of mine – who had also swindled me out of £3 by this point and made a fair few comments I would describe as racist – let me know that she lived on the top floor of a block of flats but, not to worry, because the block was only a mile or so away. Despite all this – “this” being the entire afternoon – I still feel contented that I helped this lady out, even if I have avoided her since.

Good deeds are considered selfless, but they are often not. This is because a fair number of good deeds take minimal effort; the effort is outweighed by the feeling of self-satisfaction. If anything, it is pure human profit, and as such perhaps not altruistic at all. (There are, of course, the times when we go above and beyond, when we inconvenience ourselves for others. I can summon up many occasions when friends, all over the world and in all seasons, have gone above and beyond for me.)

But mostly it’s something that, for you, takes very little, but can make all the difference to another. The teenage girl frantic in a strange city who asks for directions, or to borrow your phone. Lifting someone’s suitcases down station stairs or grabbing one end of a frazzled mother’s pram, its inhabitant blotchy-faced and screaming. Tapping a rushed businessman on the shoulder to return his wallet.

I truly believe the whole world would collapse without these interactions, or to use the American argot: the act of paying it forward. In fact, one doesn’t need to be the do-gooder or the recipient to be warmed by an act of kindness. Even reading about them can be a joy. Do a good deed today, then – even if it’s just holding a door open. And I will do one for someone in turn. As long as it’s not their entire weekly shop. Never again.