Sport has the power to save and change lives.

Whether by uniting people from diverse backgrounds, or bringing fun, laughter and a sense of purpose to otherwise desperate situations, sport can overcome many of life's most difficult problems.

I know this both from spending a lifetime working in sport, and from my role as an ambassador for Unicef, the world's leading children's organisation. As manager at Manchester United, I encouraged the players to get involved in Unicef's life-saving work for children. We were fortunate enough to visit projects when we were on tour and during private visits, which gave us glimpses into the lives of children in very different situations to our own.

I vividly remember a trip to a rescue centre in Bangkok where we met young girls who had been trafficked and forced into child labour. Some were as young as five years old, and had been through horrific experiences.

Unicef was helping them recover in safety, providing health care, trauma counselling, education, and help returning to their families if possible.

When we first arrived, these girls were shy and communication was hard. But after they challenged a few of us to a kick-about, the whole place echoed with cheers and laughter. They had forgotten, even if temporarily, about the darker things in their lives, and were able to regain something of their childhood.

Around the world Unicef uses sport to transform children's lives. Whether it is through disseminating life-saving HIV/Aids messages through football matches, or by keeping children in school through including fun sport lessons in the curriculum, or tackling violence through team-building sporting activities, the power of sport to engage children and build relationships cannot be underestimated.

I am delighted that Glasgow 2014 has chosen Unicef as global charity partner for this summer's games. I have seen for myself many young lives saved and changed by Unicef's work, and I know that they will not stop until they have reached every child. But Unicef receives no funding from the United Nations budget, and has to raise every penny it spends.

Unicef will deliver a proud legacy for the Glasgow 2014 Games. Working in Scotland, as well as across the Commonwealth, Unicef urgently needs your help to ensure that every child gets the best start in life, and is given the opportunity to grow and thrive. Every pound that you can give will help save and change children's lives. Please donate to The Herald and Sunday Herald's Children of the Commonwealth Appeal, and help us put children first.