"Ten years ago, the Army would never have acknowledged that there was a problem and a lot of soldiers with PTSD were just discharged. For me, it's almost the final piece in the puzzle," said King, one of New Zealand's most prominent mental health advocates.
Young people have led the charge towards an attitudinal change in thinking about mental health in the country, he says.
And when people like former SAS soldier and New Zealand's only living Victoria Cross recipient Willie Apiata speaks openly about his ongoing battles, King says, people tend to listen.
"Blokes like Willie Apiata, who we hold up as the bastion of manhood, humble but staunch, to come out and say, 'Hey I've got issues', that's a whole new level. If it's OK for Willie to open up and talk, then why can't a truck driver from Murupara talk about their problems?" says King, one of seven 2018 Poppy Ambassadors.
"It's especially captivating for young Maori men and women who have always been taught, for whatever reason, through lack of male role models or whatever, to be hard and staunch and hold on to your problems, to hear a guy like this speaking openly.
"When Willie says that he still has counselling once a month and every time he goes to sleep he relives it, it's not only groundbreaking, it's relieving for people to know they don't need to hold on to this stuff."
The theme for this year's RSA Poppy Appeal, 'Not all wounds bleed' extends beyond former, current, and future servicepeople, King believes.
With the ever-increasing popularity of Anzac Day, and young Kiwis interested in those who have come before us, he thinks it will help how New Zealanders react to mental health.
"Attitudinal change is huge," King says.
"Recognising there is a need and acknowledging there is a need is 80 per cent of the solution but the next 20 per cent is the most crucial part. Now with people opening up and coming forward we need to have services there to provide for them. Because if we fail on that first person, you lose that first person and the 50 people he tells, and the 50 people they tell, will have a devastating ripple effect.
"And that's where this [Poppy Appeal] money is vital. We as a nation need to demanding everyone else does something about it and looking in the mirror and saying what can I do about it? Do I really need that $10 bottle of beer, that ham roll or coffee? Or can I just forgo that and make a real difference to someone's life?"
• NZME is an official media partner of this year's Pin A Poppy campaign. Visit www.pinapoppy.co.nz to donate – including the option to get a $3 virtual poppy via text
Where to get help:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111.
Or if you need to talk to someone else:
• LIFELINE: 0800 543 354 (available 24/7)
• SUICIDE CRISIS HELPLINE: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• YOUTHLINE: 0800 376 633
• NEED TO TALK? Free call or text 1737 (available 24/7)
• KIDSLINE: 0800 543 754 (available 24/7)