Dear Blu,

I need to get serious for a moment. We'll play around a lot, we'll laugh a lot, we'll joke a lot, but there are times when we will need to get serious and talk seriously. This is one of those times.

You'll soon come to find out that I'm a bit of a sports nut. Your grandpas were, too. I can spend hours days watching sport -- it doesn't matter what sport -- and shouting at the television. And then I'll watch the replays, too, just in case I might have missed something important. It might drive your mother mad, but she's far too awesome to say anything about it.

I play a lot of sport, too. Quite poorly, in most cases, but I play nonetheless.

There's a reason I do this beyond the sheer enjoyment and exercise. You see, Blu, I think sport teaches you about life.

There's the obvious stuff about teamwork and the physical benefits and how it keeps you healthy, etc, etc, etc. And that's important. But there's more to it than that.

Shortly after England got beaten by Iceland in one of the greatest upsets in soccer's recent history [the significance of this might be lost by the time you're old enough to read this, but anyway], SuperSport presenter Robert Marawa summed up perfectly just how sport can impact those who play it.

"Football will humble you. Football will teach you many lessons."

- Robert Marawa, South African broadcaster.

He might have been speaking about soccer, but it rings true no matter what the sport.

It will humble you and it will teach you many lessons. You will learn to lose and you'll learn to win - and you'll find out a lot about yourself when either of those things happen. You'll lose when you should have won, and you'll win when you should have lost. You'll learn to shake the hand of your opponent when you don't really want to, and to thank the match official even when you think you've been hard done by. You'll learn that you're only as good as the hard work you put in (and that even that might not be enough), and that your natural talent is just the starting point.

You'll learn that it's not always about you. Because the sport is bigger than those who play it. Wayde van Niekerk won gold and broke the world record in the men's 400m at the Olympic Games, and in doing so became a national hero. More than that, though, he became a hero to a largely marginalised group of people who are far-too-often victims of racist caricatures and stereotypes. His win was huge for him - it really was - but it was also huge for the coloured community. Sport is often bigger than the individuals who do it.

Wayde van Niekerk posted this on Twitter after winning Olympic gold at Rio 2016.

It'll make you deal with intense - and often undeserved - criticism. Caster Semenya will probably no longer be running by the time you are old enough to even understand what I'm talking about, but she'll continue to be spoken about...and probably in negative terms by non-South Africans. You see, Blu, Caster produces more testosterone than other woman athletes, and this fact alone has led to her being labelled a man, as being unfit to compete against other women. She's faced attacks just for the way her body produces a particular hormone. The fact that she's a black woman is probably also a factor in the criticism. It's unfair. How has she responded? She's shrugged it off and won 800m gold for her country. There's a lot you can learn from exceptional women like her..

Caster posted this on Twitter in the build-up to her 800m heats in Rio.

Blu, I don't know what sport you'll be interested in -- or even if you want to play sport at all. Even as I write this I'm not even sure if you're a boy or a girl, or exactly what day you're going to be born on. But I would really like you to play sport. Any sport. It doesn't matter what it is; it doesn't even matter if you're good at it. But it will teach you many lessons, and all I want is for you to learn as many lessons as you possibly can.

Love you,
Dad