Not a single woman in the whole world goes through her day - every single day - without, at some point, thinking about her own safety, without making a judgement call - large or small - about how to stay safe.
Equality and opportunity are interlinked with our daily experiences of safety, whether in the office, the home, our schools or walking the streets. As women, we are constantly calibrating; deciding whether it is too dark, too quiet, too risky or too uncomfortable to stand still or too dangerous to move.
As we pick up on this year's theme to press for progress, our focus understandably lies on safety and security, and there is much that needs to be done.
This year in the United Kingdom, we recall the long fight women took on to achieve the vote for some privileged women, achieved in 1918. As we assess that landmark, it can only be through the lens of what still holds women back in the daily fight for equality.
Over the past year, Theirworld has been looking at how we can rewrite the hidden codes that hinder progress on equality. Many of those hidden codes have now become visible. We have seen the abuse of power exposed across all sectors, whether it's high-profile Hollywood stars, businesses, or more recently the charity sector.
No area of society and work should be excluded from the highest standards of safeguarding and behaviour. Recognise it. Tackle it. End it. Change the culture.
We have seen people around the world finding the courage to share their own stories and experiences - and a growing, diverse and powerful movement through #metoo, #timesup and other campaigns. These movements are bringing to light the issues girls and women still face in their daily lives.
But every woman's experiences differ. We constantly wrestle with what needs to change and we may have alternative solutions and different ideas but I truly believe the spirit of protest and the search for justice is alive and kicking.
And for many individuals there is layer upon layer of injustice heaped on them because of race, gender, disability, religion, sexuality - with the very real complexities of intersectionality, our experiences are different - but we can share our stories, and look for the actions we can take together to deliver real change.
Around the UK women are running their own companies, leading great institutions, creating new innovations or seeing their talents shine across the arts; but we know we are a long way from equality. Equality in pay, in opportunity and in the daily culture we experience all the way through our society.
It is not just the challenges girls and women in the UK face every day that we want to confront - we are also pledging support to girls and women around the world. For Theirworld this means the fight to ensure they receive an education and proper health care.
In some countries, young girls face the threat of violence just trying to make their way to school and an even greater risk of early marriage, child labour or trafficking if they don't make it. Just recently, we've had the horrific news of the abduction of another 110 girls from their school in Dapchi, Nigeria, and Theirworld is battling to see the Safe Schools Initiative restored so that girls can attend their classrooms with confidence and without fear.
This year, we have to resolve to change the culture, to create our own safety, and to take action on behalf of the most vulnerable girls and women to ensure they can safely go to school, to work and be at home with the chance to fulfil their own potential.
Sarah Brown is the Founder and President of the children's charity Theirworld and Executive Chair of the Global Business Coalition for Education.
Any views expressed in this article are those of the author and not of Thomson Reuters Foundation.