Princess Kate today launches a mission to create a happier, healthier society through a major new project for her early childhood foundation.

It marks a significant step on her return to work following her battle with cancer as she calls for all to “invest in humankind”.

She says to “create a physically and mentally healthier society, we must reset, restore, and rebalance”.

Her heartfelt message comes in a ­personally penned foreword to a 106-page report, ahead of a public launch next week — her first such engagement for her children’s projects in 14 months.

Her early years initiatives are described as the “golden thread” of her work this year and she will be seen up and down the country promoting it.

The princess was briefed on the progress of the Shaping Us report, which has taken almost two years to research and release.

It comes after Kate — who last month revealed her cancer was in remission — carried out three royal engagements last week, with sources close to her insisting she was embarking on a gradual recovery rather than returning to full-time work.

Kate is said to be excited to have a chance of shining a light on early childhood and the work of the centre after conducting her highly personal visit to the Royal Marsden Hospital.

In her foreword for The Royal Foundation Centre for Early Childhood’s new Shaping Us Framework, the Princess of Wales says: “Modern society is complex.

“At times, it can feel like the world is filled with mistrust and misunderstanding, leaving many people feeling isolated and vulnerable during difficult times.

“The impact of this — poor mental health, addiction and abuse — can be devastating, for individuals and for society.

“If we are to address this properly, if we are to find real, lasting solutions to these deep-rooted challenges and create a physically and mentally healthier society, we must reset, restore, and rebalance.

“We must invest in humankind. As human beings, we are at our best when we are surrounded by love, safety, and security.

“We thrive when we are ­connected to one another; when we feel like we belong, feel seen, heard and accepted for who we are.

“That means taking a profound look at ourselves and our own behaviours, ­emotions and feelings.

“It means getting much better at ­acting with compassion and empathy towards one another, to help us bond and maintain lasting relationships that bring meaning to our lives

“It means better understanding of how we can protect and build upon what connects and unites us, so that we can find new ways to strengthen communities.

“And it means acknowledging that society is something we build together, through the actions we take every day.

“At the heart of all of this is the need for us to develop and nurture a set of social and emotional skills which we must prioritise if we are to thrive.

These skills continue to grow throughout adulthood – it is never too late

Princess Kate

“This report sets out a universal approach to understanding these core social and emotional skills throughout all stages of our lives.

“It highlights the skills which are the bedrock of any healthy, happy society and it helps individuals and organisations understand the ways in which they can contribute to making this conceptual model a living, breathing reality for everybody.

“It lays out why early childhood is such a golden opportunity to give the next generation the most positive start in life.

“But it also shows that these skills continue to grow throughout adulthood – it is never too late

“The Shaping Us Framework is designed to provide an accessible way of focusing on social and emotional skills.

“It can be used by organisations of all shapes and sizes to design and deliver interventions that raise awareness across society, and to support the development of these critically important skills for people at all stages of life

“Most importantly, it shows that we can all play a vital part in building a more loving, empathetic, and compassionate society, and a world with humanity reconnected.”