Most of us will know at least one person affected by mental illness. It's important to understand it and also to understand how we can keep a healthy mind.
Mental illness affects all of us in some way. It's in every family. Every school. It's the girl who sits up crying every night but doesn't know why. It's the boy who cuts his arms cos it's the only time he forgets his parents' fights. It's the teacher who drinks too much. It's the babysitter with her fingers down her throat in the bathroom.
One in four people will experience some kind of mental health problem over the course of a year - including celebrities, sports starts and political figures. Noone is exempt.
Mental illness describes a million different ways in which we can stop thinking straight. sometimes for long enough and badly enough that we can't function in our day-to-day lives. It affects one in ten teenagers.
Most mental illness is caused by a combination of two things: biology and circumstances. We are born with a susceptibility to mental illness. That's the biology. And then life treats us badly and it affects us, maybe not for many years.
How (and how badly) we get affected is different for everyone. We may get depressed, even suicidal. Or feel anxious and frightened all the time. We may take drugs or take risks with our health. Anything is possible.
This is a severe mental illness. We stop seeing things as they really are and we may hear things that other people can't, or believe things that are bizarre and untrue, which affects our behaviour. About one in a hundred of us will be diagnosed with this illness at some point.
The best we can do is to look after ourselves. Eat well, exercise, relax and enjoy life. What is good for our body is good for our mind. And if we think we're starting to wobble, we should get help. All mental illness can improve with treatment so speak to parents, trusted relatives or a GP, in confidence as soon as you suspect something is wrong. It can be daunting, but the sooner we get treatment, the sooner we can get better. Don't suffer in silence.