On May 22 last year, Vitidnan took the final few steps to become the first Thai to stand on the 8,848-metre summit of the world's highest mountain.
From his rucksack he took a framed picture of His Majesty the King he'd carried with him and held it aloft.
"Who is he, your father?" enquired a foreign member of his team.
An exhausted Vitidnan felt tears well in his eyes, and then smiled broadly: "He is not only my father, but the father of 60 million Thais."
His companions looked on in silence as he shouted across the Himalayas, "The King of Thailand! He is the King of Thailand!" Then they broke into applause.
Repeated cries of "Long live the King, long live the King!" echoed among the peaks as Vitidnan unfurled the Thai flag presented him by Her Royal Highness Princess Maha Chakri Sirindhorn and held it out into the wind.
"It was a once-in-a-lifetime experience," says Vitidnan, a 41-year-old freelance TV producer in Bangkok.
"You have to risk your life for this big a challenge. You need a strong sense of self-awareness to confront any danger."
Before attempting an ascent of Everest, most mountaineers practise on six other peaks, but Vitidnan just couldn't afford it.
"Climbing those six summits would cost about Bt4 million, and I couldn't handle the expense, but I worked on a TV reality show in Vietnam, and they gave me the chance to do some serious climbing.
"I'm not a professional mountaineer, of course. I just really wanted to achieve a very difficult goal for the pride of the Thai people and to celebrate His Majesty's 60th anniversary on the throne.
"Standing atop Mount Everest, I felt as if I could fly," Vitidnan says. "It was such a delight, not only in the spectacular beauty of the landscape, but also in discovering the magical power hidden inside each and every one of us.
"It's said that if you can reach the top of Everest, you can go beyond any human limitation.
"On the top of the roof of the world, I wanted to shout for joy - that even a Thai can accomplish such a daunting task. It was tough and risky, but it can be done if you're determined."
It was vindication indeed for Vitidnan, who'd spent almost two years trying in vain to interest sponsors.
"No one paid any attention to my honest intentions. Some said I'd better try something else that wasn't so risky.
"But I never gave up. My determination faltered and my hopes began to fade, but my dream was revived thanks to the support I found in Vietnam.
"I ran a TV reality show there and the producers agreed in return to help me with the financing and support staff for the Everest ascent."
In the open challenge they mounted, Vitidnan says, 5,000 Vietnamese applied for a crack at the biggest peak in the world. Twenty were chosen to climb Mount Kinabalu in Malaysia, and from these, six finalists earned the chance to scale Mount Kilamanjaro in Kenya.
Everest loomed ever larger.
"Ahead of facing the biggest challenge in my life, I had to prepare physically and mentally," Vitidnan says.
"Every day I underwent weight training, ran 12 kilometres and carried a gallon of water on my back while running for two hours up and down a 40-storey building."
Every year at the Kathmandu City Hall, the Nepalese government presents gold medals to those who reach the top of Everest - the Everest Summiteers.
Vitidnan will be there on May 29, and all of Thailand will be there with him in spirit.