Mrs Sanderson is the fifth governor to be Patron of the not-for-profit group, which works with young people aged 12-25 to help them overcome issues associated with depression, anxiety, self-harm and suicidal thoughts.
The journey started when Ronald Woss and Peter Fitzpatrick combined to bring a NSW initiative called Youth Insearch to Perth.
It hosted weekend camps for young people where they could feel safe and included.
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READ NOWAfter six years, the concept had gained so much momentum that in 1994 the duo forged their own path to co-establish Youth Focus that was independent to WA.
Last Tuesday, Mr Woss shared his motivation for initiating the concept.
His daughter Melanie committed suicide in 1988.
Mr Woss said the loss of Melanie made him realise that suicide and depression did not discriminate.
He said it did not matter what sort of education you had or how financial you were.
Mr Fitzpatrick was caught off-guard at the birthday celebrations.
"I haven't seen Brooke for 15 years," he said.
Brooke Chapman, who spoke at the event, attended Youth Insearch camps and then Youth Focus activities as a teenager after losing her dad and surviving a brain tumour.
Ms Chapman now works for Youth Focus.
The Burswood-based charity released a book of 21 stories from the past 21 years to commemorate the milestone. Visit www.youthfocus.com.au.