Smaill has been diagnosed with an autoimmune condition that affects his muscles.
He has begun a course of steroid treatment, which is expected to take 18 months to two years to complete. At that point it is hoped he will be back to 100%.
It comes less than a year after guiding Southern United to the women’s South Central Series title, the Covid-adapted version of the national league.
While it had been tough to walk away from a shot at a full national league title, he felt he needed to focus on his health, Smaill said.
"I was just finding it was just too much for me to try to commit to the football and then focus mainly on my health," he said.
"So I decided, in consultation with the doctor and my family, that I needed to focus on my health and get that right first.
"It was a tough decision. I was really keen to have a crack with the girls again, and see where we went in a full national league.
"But I really didn’t think I could do the job justice when my main focus really needs to be on my health," Smaill said.
Smaill, who is also the Dunedin City Royals premier women’s head coach, has had the past month off work and is in Hawaii at present.
He will be back for this weekend’s Kate Sheppard Cup semifinal against the Northern Rovers in Auckland.
Smaill said he noticed the problem when he tore his medial cruciate ligament while playing masters football.
It was taking a long time to come right and he was increasingly in pain.
His doctor diagnosed his condition and since having his break from work, and starting on steroids, he had begun to feel better.
It had been difficult coaching in recent weeks, and he was grateful for the support of assistants Una Madden and Richard Smith, as well as manager Patrina Roche.
"It was pretty tough," he said.
"I was hobbling along to trainings and stuff like that. I found it hard to focus — the pain was pretty bad at times," he said.
"Just wondering what’s wrong with me, am I just a hypochondriac? It gets in your head.
"You start doubting yourself and, are you imagining stuff?"
He hopes to continue with the Royals through to the end of the season.
While not being directly involved with Southern, he said he would remain available to the new coach to provide advice and would get along and support as many games as he could.
