Right now, there is a mental health crisis among children and young people in the UK. According to new polling by HuffPost UK, a third of young people aged 18-24 say that they have had a mental health problem over the last year, while the recent Millennium Cohort Survey suggested that almost a quarter of girls and one in ten boys show signs of depression at the age of 14.
Sadly, there is evidence that problems are getting worse. The number of under-18s arriving in A&E with a psychiatric issue has more than doubled since 2010, while 90% of school leaders say that they've seen an increase in anxiety, depression and low mood over the last five years.
Mental health problems in university are also on the rise, with the rate of students disclosing mental health conditions having increased almost five-fold in ten years, alongside an alarming rise in suicides.
Everything around us can influence our mental health. We know that young people face a huge range of pressures, including stress at school, college or university, bullying, body image issues and the pressures created by social media. Difficult experiences in childhood - like neglect, bereavement or domestic violence - can also have a serious impact, sometimes several years down the line.
While there is greater awareness today than in the past about mental health, it can still be extremely hard to reach out for help. To make matters worse, when children and young people do seek support, specialist services are often overstretched.
Because it's so difficult to get treatment in some areas, problems can escalate. All too often, we hear from young people who have started to self-harm or dropped out of school during the long wait for treatment.
At YoungMinds, we work with young activists and families to campaign on mental health. Together we call for political change, we work to improve services, and we spread the message in schools, at events and online about how to look after yourself. We also run a parents' helpline, which provides a lifeline to parents and carers who are worried about a child or young person.
But we need your help. Having a mental health problem can be an incredibly isolating experience, and we want you to help us spread the message that, if you're struggling to cope, you're not alone.
On World Mental Health Day - Tuesday 10th October - we are calling on people up and down the country to take part in our #HelloYellow day. We want as many people as possible to wear something yellow, and to share a message of support for children and young people who are struggling with their mental health.
Across the country, hundreds of schools and businesses, as well as thousands of people of all ages, have already signed up. Together we hope to share more than 10,000 messages on the day, and to raise much needed funds to support our work. We'd be delighted if you are able to join us and take part.
And, if you're struggling with your own mental health, don't suffer in silence. Talk to someone you can trust - it could be a friend, a family member, a teacher, a doctor, a counsellor or a helpline - or go to the YoungMinds website for more information about how to find support.
To find out more about #HelloYellow, go to youngminds.org.uk/helloyellow