Too often, we run our relationships like co-operatives. If I cook, you do the dishes. If you put the rubbish out, I'll do the laundry. If you drop the kids at school, I'll pick them up.
It's all about give and take, emotional profit and loss, balancing the books.
And for some reason if one of you is being too nice, doing too much and the other is lagging behind, this is seen as unfair and grounds for a big sulk and an argument about sharing.
We might buy flowers for our husband, but really it's because you wanted some flowers for the lounge and the unnecessary expense can be much better explained if it is a gift.
We might make breakfast in bed for our husband if (a) it is his birthday (b) it's Father's Day and (c) we went out last night, didn't get home until 2am and forgot to text where we were.
We might lavish him with praise about his appearance or the way he manfully hung the washing out, but that's only because you want him to take you out to dinner.
What if we all just started being kind to each other without expecting something back in return?
My simple acts of kindness were very small. I folded the washing and put his clothes away in his drawers rather than leaving them on the bed for him to do. I did the dishes even though it was his turn three nights in a row.
I made him hot chocolate before bed. For a change, I didn't insist on a foot rub while watching TV. I washed his car. I ironed all his shirts and hung them up in the wardrobe. I made his lunch and left it in the fridge for the next day.
And as I was doing it I heard a female voice in my head saying: "You're not his slave. Treat 'em mean, keep 'em keen." And another demanded to know when I'd decided to time-travel back to the 50s.
But I didn't feel downtrodden or slavish. No one held a gun to my head and made me be kind. Instead I felt great. I received a wonderful mood cocktail of virtue combined with a gentle halo effect of beneficence.
And my husband, once he got over the shock, really liked it. I think he felt appreciated and loved, if a little confused.
Being kind is not about whether you see yourself as a feminist. It has nothing to do with politics or values. Or topping up the karma bank. It's just about being a nice human being who stopped for one moment, took themselves out of the equation and wondered what another person might find pleasant and wonderful.
I may be counting the days until my supportive wife challenge is over, but I'm quite liking being kind.