Son will lead out his side on Thursday in the tournament's second match after co-hosts Mexico kick-off the showpiece against South Africa.
"The guys are so fired-up for this match, and I actually have to calm them down," Son said at the pre-match press conference in Guadalajara.
"I hope our hard work will bear fruit, and I think we absolutely deserve it. The vibe is tremendous, and I can feel it from the eyes of my teammates.
"Every World Cup match is so important that, as a player, you would stake your life on it. Tomorrow, we will give everything we've got and more."
Former Tottenham star Son, 33, comes into his fourth and possibly his last World Cup after a poor season for his new club, Los Angeles FC, scoring just twice.
He said his excitement for football's global showpiece never dimmed.
"My mindset is similar, whether it's my first or last World Cup. I feel like a child again," he said.
"I have never once said this is my last World Cup. The most important thing is to do my job. People can say whatever they want, and I will choose my path wisely."
South Korea will face Mexico on June 18th before South Africa on June 24th in their final Group A match.
FIFA World Cup 2026
The 2026 World Cup took place from June 11th to July 19th in the United States, Canada and Mexico. The tournament featured 48 national teams and was won by Spain, who beat Argentina in the final.
Full schedule and results | Group standings and bracket | Past winners of the tournament | Our team of the tournament | About the 2030 World Cup