Hey you! Yes you! Did you know you're a real life, breathing human who beat thousands of other sperm to become a little embryo thing that became a life? And that all the atoms in your body have been around since the earth started? And that the fact that you can read this, and process this means you have a brain that is full of millions of nerves that all carry information around your body?

You are biologically amazing. Humans are pretty cool, not quite as cool as orca whales, but still pretty cool when you think about. While you're reading this, someone on the other side of the world is reading this as well.

So if we're all so cool, why don't we love ourselves? It's so easy to fall into a pit of hatred for yourself, and as teenagers it's easy to think that your body is worthless and useless. It's easy to say that you're ugly and stupid, and actually loving yourself can feel next to impossible.

But let's do the maths right now. You. You're part of a seven billion and ever growing mass of people, and yet there are things you do that no one else can. That laugh you hate because it's too loud, no one else can replicate. Those stretch marks you think are disgusting, totally unique to you. You are incredibly unique, and there is no one out there exactly like you. And isn't that one of the most amazing things ever?

Without you, so many things wouldn't have happened. Small things, things you probably don't even think about. Maybe you made someone smile today, or you wrote a new chapter of your book that made someone's day. Without you there to do that, that would never have happened.

You matter. You matter so much. Learn to feel your importance, feel it heavy on your shoulders. Learn to look in that mirror and tell yourself that you mean something. I believe everyone has a purpose in life, you just have to wait and see what it is.

So rule ten of surviving Teenagehood: roses might be a bit expensive, but sometimes we need to remind ourselves to love our bodies and our minds. It's not a funny rule, but it's probably the most important one in this whole book.