This week, 20 MPs in the new parliament were given the chance to campaign for a change in the law on an issue they really care about. It goes without saying that Brexit will dominate politics and public debate for the next two years. So this is a unique opportunity for MPs who are passionate about domestic issues.
Working for a children's charity, there are endless things I'd want to change. But the key to success with a Private Member's Bill is to choose something with public and cross-party support. An issue on which even the government would agree that the time to act is now.
That's why NCB has worked with YoungMinds to develop a draft Bill on Wellbeing in Schools.
No-one disputes that there is a mental health crisis in our classrooms. On average three children in each class has a mental health problem, one in 12 young people deliberately self-harms, and rates of depression and anxiety in teenagers have risen 70 per cent in the last 25 years.
Being young in today's world can be tough: exam pressures; 24-hour social media and cyberbullying; fears about the competitive jobs market; and economic uncertainty.
For some young people the problems are much more acute: disability; poverty, bereavement, neglect or abuse.
Teachers want to help. Headteachers and governors understand the problem. But resource is shrinking, and demand is rising. Specialist services have long waiting lists.
So, what needs to change?
Schools must have the necessary resource to promote emotional wellbeing, prevent problems escalating and work with specialist services to support young people with mental health conditions.
In May, the Education and Health Select Committees published a report calling for a "whole school approach", with implications for staffing, training and focus in the curriculum. This, the MPs wrote, is in the best interests of children.
Both government and opposition support better mental health provision in schools. But it will take more than fine words, or even changes to government policy to overcome the pressures on schools and health services.
That's why we have proposed a clear legal duty on all schools (including academies) to follow a set of principles for promoting good mental health and emotional wellbeing. Naturally this would have cost implications, which would be met by national government. But this is a sound investment. Helping schools keep children healthy and happy will lead to huge savings for the NHS later.
Enver Solomon is director of external affairs at NCB