"It means so much to me to qualify for the US Amateur," said McCall shortly after his round.
"I achieved some massive goals in so many areas the last few days and weeks."
The former New Zealand Stroke Play and New Zealand Amateur Champion said his final round 67 was the sort of performance he had been working towards for months.
"I played extremely well today but more importantly my mental side was superb," he said.
McCall has been working with sports psychologist David Galbraith and said that work paid off under pressure.
"I have to thank David. I kept patient and for that I have seen results. I went five under on the back nine to qualify. That was mentally the best performance of my life."
The Kiwi played the qualifying event in Texas on the back of finishing tied for 20th at the Trans Miss Championship on his first trip to the United States. His best result in the UK was a runner-up finish at the Berkshire Trophy.
He will look to become the second Kiwi to win the US Amateur after Danny Lee.
McCall feels like he is in good shape to contend for one of the biggest prizes in amateur golf.
"My form is really good. The key to my success was how hard I have been working in the gym and in practice, practice rounds and the work I am doing on course physically and mentally."