"As far as I know he had no history of depression, but he obviously had lost his brother, and farming brothers in particular are very close," says Mrs Blyth, 43.
"I talked about it with my cousins at the funeral - let's do something, let's not just give $100 to the Mental Health Foundation."
Although she lives in Brisbane with her husband and four children, she and several cousins formed the core of a small group of cyclists who biked from Bluff to Cape Reinga to raise $30,000 for the Mental Health Foundation in February 2011.
Another rider in that event, actor Aidee Walker, led a second ride in 2012 which raised $46,000 for the foundation's new programme of teaching "mindfulness" in schools.
Mrs Blyth is back to lead a third ride which leaves Bluff tomorrow for Cape Reinga, aiming to raise $50,000 for mindfulness education.
She said the ride's biggest goal was to make depression visible so that people could talk about it.
In 2011 more than 100 people rode part of the distance with the core group. One farm worker who rode for a day said the fact that the ride was coming through town gave him the confidence to tell his mates about his struggle with depression.
"I like to think that the ride being out there, putting the issue out there, helped that person," Mrs Blyth said. "The aim has always been to raise awareness more than to raise money."
Here we profile the other nine riders.
2. Tamzin Hawkins
Auckland fashion designer Tamzin Hawkins is joining this year's ride for her 88-year-old grandmother - and for Charlotte Dawson.
Ms Hawkins, 29, worked for Trelise Cooper when Ms Dawson modelled garments for the fashion label a few years ago.
But when she set up her own label, Mavis and Osborn, Ms Hawkins named it after her grandparents Mavis and Brian Osborn Mansell, of Opotiki. Mr Mansell died two months ago and would have turned 104 today. Mrs Mansell suffered postnatal depression after giving birth to her third child, Ms Hawkins' aunt, 57 years ago.
"We called it the 'baby blues' in those days," Mrs Mansell told the Herald this week. "I just got gloomy, that's all. They gave me shock treatment, which was pretty awful, they didn't used to give us anaesthetic in those days."
Ms Hawkins has also had to cope with traumatic events. Her parents split when she was 9 and she had to move with her mother from Raglan into Hamilton. She has recently had counselling, almost 20 years later, which has helped her to understand the emotions she felt at the time and finally "let those feelings go".
A friend, Aidee Walker, persuaded her to take part in the 2012 Ride out of the Blue, and this year she has become a co-organiser with Alison Blyth's cousins Sally and Alan Smith.
"It wasn't looking as though anyone was going to organise it, and then Charlotte Dawson took her own life, and I had worked with Charlotte when I was at Trelise Cooper, so that's what made me go, 'Right, this ride has to happen again,'" Ms Hawkins said.
"It's not good enough that someone like Charlotte, who was trying to do so much with anti-bullying campaigns, didn't have support for her own bullying."
3. Inspector Dave Glossop
South Auckland police inspector Dave Glossop still gets a card every year from a man he talked out of suicide five years ago, when he was a member of the police negotiation team.
"We are specially trained to deal with people who are suicidal, as well as people who are involved in hostage-type situations," he explains.
"I had a guy that I talked down off a tower in West Auckland, he was wanting to try and jump off. I still get cards from him around his birthday to tell me he's another year older."
Mr Glossop, 49, and his wife have four children aged 18, 17, 15 and 7, so he feels a special empathy in situations where young people are threatening to take their own lives or, tragically, have done so.
He is also an avid cyclist, so he was a natural to take part in the first Ride out of the Blue in 2011 alongside fellow South Auckland cop Kate Smith, one of the cousins who resolved at their cousin's funeral in Taranaki in 2010 to do something to help people with depression.
He missed the second ride in 2012 because he was on a four-month deployment in Afghanistan, training local police in intelligence work. But when Alison Blyth asked him to ride again this year, he agreed because he still sees a desperate need.
"There have been a couple of what we call 'contagions' in some of the schools in my area of responsibility in South Auckland, and I'd also had a staff member from Otahuhu commit suicide, so the whole thing was really, really raw in my head."
He said the whole police force supported the ride, which starts most days from the police station in each town along the route.
4. Sally Smith, 65, is another one of the cousins who resolved to do something concrete for people with depression. She and her husband, Alan, who live at Sandspit, east of Warkworth, participated in the second ride in 2012 and Mrs Smith is the co-organiser of this year's ride with Tamzin Hawkins.
5. Alan Smith, 70, did a bit of cycling in his 20s, "half a lifetime ago", and has got back into it since 2010. "I obviously like two-wheeled transport, as I ride a Suzuki 650 motorbike when I am not busy training for Ride out of the Blue," he said.
6. Rebecca Marley, 27, of Christchurch, has fought battles with depression, anxiety and anorexia, which saw her admitted to Christchurch's Princess Margaret Hospital. "I am a stronger person because of these battles and it is now my mission to share this with everyone I meet on this journey," she said.
7. Dahlen Phillips, 27, is an Australian now living in Wanaka. "Cycling provides me with freedom, plenty of exercise and fun times with friends," he said. "Depression and suicide are very serious issues, a great way to address them is education, early intervention and prevention."
8. Corinne Dolan, 33, is a personal trainer, mother of four and one of Alison Blyth's Brisbane-based friends who have come over with her to join the ride. "Riding has given me a release, a confidence builder," she said.
9. Claire Rabaa, 33, another Brisbane friend of Alison Blyth, is a mental health social worker who hopes the ride "will be able to help people talk about mental health and realise that early intervention and prevention are so important".
10. Kevin Adamson, 62, was born in New Zealand and "shifted to Australia a long, long time ago but still consider myself very much a Kiwi". He is doing a PhD in molecular biology at the University of the Sunshine Coast, runs a small flower-growing business, and said: "I am looking forward to joining the ride this year, to not only see our beautiful country, but to help raise awareness of the often overlooked problems of depression and suicide."
How to donate
• www.givealittle.co.nz/cause/rootbnz
• www.rideoutoftheblue.org
• www.facebook.com/rideoutoftheblue