Fenn, 23, speaks from experience. The former cricketer has taken on the challenge of breaking world running records to get people talking about mental health, and it all started when he found himself having thoughts of ending his life at 18.
"I found myself in an apartment in London alone in the middle of winter. And I was struggling with thoughts of taking my own life. Because I had no purpose and no reason to keep going," he tells the Herald.
"Cricket was part of my identity at the time and when it wasn't going well, it literally felt like the end of the world. I'd put everything into it and then it was not worth it."
It was running that helped him find his feet again, inspired by a chat with a mate at the gym.
"I remember lying in bed the next night and having the first positive conversation with myself that I'd had in two years," he recalls.
That conversation inspired him to start challenging himself - and New Zealanders - to do something active for mental health.
In March this year, he ran 654km - one kilometre for every Kiwi lost to suicide in 2020.
He ran 50km for five days in a row across the North Island and ran continuously for 24 hours wearing a 24kg weighted vest.
Then he ran up and down the steepest street in the world, Dunedin's Baldwin St, aiming to reach the height of Mt Everest.
Finally, this month he announced on Instagram that he would begin running and wouldn't stop until 1 million people had commented on the post. It doubled as the world record for the longest single-stage run ever completed.
"The running actually doesn't matter. It's just a vehicle to carry the message that we're trying to encourage people to pay attention to," Fenn says.
According to the rules laid out by Guinness, the run had to be at least 100km every 24 hours, and he couldn't stop for more than two hours at a time, preventing him from sleeping.
But it wasn't long before the pressure of breaking running records caught up with him, he says - this latest run ended in a trip to the hospital.
While he felt prepared beforehand, around 421km in he had to stop due to foot fractures. "It was a 10 out of 10 for pain for hours on end."
"I've done three big challenges in the last eight months and it's taken a big toll. I've been putting change in the mental health space above my own mental health and neglected that, and that's really tough.
"It's a little bit ironic," he laughs. "When you're pushing for change and encouraging people to do things. That's why I feel like it's actually really important for me to say that, actually I'm tired and I need to go and rest."
In September, the Ministry of Health launched a long-term plan aiming to transform New Zealand's approach to mental health.
"This is bringing together the two biggest issues in New Zealand health, and we need to be in it for the long run."
A spokesperson for the Ministry of Health acknowledged there has been increasing pressure on the mental health and addiction sector for some time.
"This is not new, and we have seen an overall increase in the numbers of people accessing mental health and addiction services as awareness of mental wellbeing grows," they told the Herald.
"This demand on services can result in people having to wait for support."
While mental health has come a long way and is no longer the taboo topic it once was, that's still not enough according to Fenn.
"I think we talk about mental health, but we don't do a whole lot. Yes, you reposted this thing on your Instagram, but did you then go and have a conversation and check in with someone? And that's what I've started to try and do is leave people with an impression that keeps them thinking about it."
There's no clear solution when it comes to the mental health crisis, he says.
"It's a difficult question. It's a complex problem, and I don't know the answer."
"The biggest thing is not just talking about it, but actually having real discussions with people and doing things for them.
"I feel like we've seen that over the last five years. But there's a really long way to go."
Where to get help: • Lifeline: 0800 543 354 (available 24/7) • Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7) • Youthline: 0800 376 633 or text 234 (available 24/7) • Kidsline: 0800 543 754 (available 24/7) • Whatsup: 0800 942 8787 (12pm to 11pm) • Depression helpline: 0800 111 757 or text 4202 (available 24/7) • Anxiety helpline: 0800 269 4389 (0800 ANXIETY) (available 24/7) • Rainbow Youth: (09) 376 4155 If it is an emergency and you feel like you or someone else is at risk, call 111.