She was the key speaker at a conference being held at The Park Inn Hotel.
She thanked volunteers for their dedication in helping people with complex mental health needs.
Princess Anne told members of the Youth Support Service: "One of the things that impresses me the most is the treatment of individuals, as individuals. We have to believe that youngsters of any age have the ability to make positive changes.
"The voluntary sector has such a lot to offer. Part of the success comes from the mentor or volunteer who has taken their time to help. Work at grass roots level is about volunteers and we rely wholly on them."
"I'm really grateful for your enthusiasm and support in coming. It is a difficult subject but partnership working can make a difference.".
The Princess Royal was greeted by two pupils from Randlay Primary school when she arrived at the hotel.
Brothers Jack, eight and Tom even, were introduced to her by their father, Adrian Pickard, district director of the hotel.
Presented with a bouquet of flowers Princess Anne said: "This is very kind of you, thank you very much."
After meeting The Princess Royal, the brothers said: "It was really exciting. She said thank you for the flowers and put them in the car so she could take them home."
Mr Pickard added: "They got special permission from their school to come along this morning and have really enjoyed themselves."
Lady McFarlane, Chair of the Trustees, the princess for her support, saying she had given the room plenty of "food for thought".
She added: "You have visited every year and we are delighted you have agreed to support us for another three years. We are all honoured and delighted you have attended today."
MP for Telford, David Wright, said: "This is a really important initiative to support people with mental health needs and its great that The Princess Royal is part of this in her role as patron. It is also wonderful to see her back in Telford."
Telford Mayor Leon Murray is also trustee of YSS. He said: "I became a trustee of the charity in 2000. It is brilliant, it brings together the expertise of organisations and that's wonderful."