The former Dunedin swimmer narrowly missed selection when his times for the 200m freestyle (1min 49.40sec) and 200m butterfly (1min 59sec) at the national championships were just short ofthe qualifying standard.
McMillan (22) had joined Jan Cameron's training squad in Auckland and expected to make the Olympic team.
"It was pretty hard to take, after my move to Auckland," McMillan said.
"I was shattered and didn't train for two weeks. I needed time to reassess my goals."
The opportunity to compete in surf life-saving again with the St Clair club came along at the right time and gave him another target to concentrate on.
"It was a blessing in disguise for me," McMillan said.
"I'm excited about surf life-saving and it gives me the chance to train and compete with a different group of friends."
The world surf life-saving championships will be held from July 20 to 26.
The pool events will be held in Berlin and the beach at a beach on the Baltic Sea.
The swim championship in the pool requires swimmers to tow manikins that weigh upward of 45kg, swim under obstacles, and wear large fibreglass fins to complete underwater swim distances.
McMillan has been a member of the St Clair Surf Life Saving Club since he was a pupil at Otago Boys High School and has remained loyal to the Otago club.
New Zealand coach John Bryant said McMillan brought power and speed to the New Zealand team.
"He is swimming faster than Moss Burmester was at the same age in both the butterfly and freestyle," Bryant told the Otago Daily Times.
"I believe that Andy will go close to breaking the world record for the 200m obstacles and add a lot of pace to the three relays in Germany."
McMillan trained with Cameron's High Performance squad until the Olympic trials.
But when he failed to make the Olympic team he went down to the national squad that trains on the other side of the pool.
"I couldn't take it emotionally to train with the Olympic squad," McMillan said.
"I needed a fresh start."
McMillan's target after the world surf life saving championships will be next year's world swimming championships in Rome.
