The Pramac Ducati rider quickly left his base in Andorra and returned to his native Queensland upon hearing that that the start of the MotoGP season had been delayed.
Now staying with his parents in Townsville, Miller has been able to use the favourable autumn weather conditions in Australia's north east to continue a pre-season style training regime.
And he says that's important, given that he's struggled to shed unwanted weight in the past.
"I'm not going to lie, it does test your motivation levels when you don't have a specific time or date to aim towards," he said in an interview on his website.
"You spend the winter getting fit, getting ready, you've done testing and then it all just stops. It feels like you're stuck in purgatory.
"My training programme hasn't changed [in Australia] – I'm still cycling and I'm still running, and I've made a point of getting up early in the mornings and getting into it.
"[It is] easy up here because it's warm too, that definitely helps.
"It'd be easy to lose motivation, train a bit less, put some kilos on where you don't want to… that's definitely something I'm trying to avoid because in the past I've struggled to get weight off if I put some on.
"I've worked really hard on that aspect of my riding so I'll keep things where I can, that way I don't have to push as hard later to be as close to top shape as I can be."
As well as training Miller says he's been spending his time tinkering with bikes, riding some motocross, and generally enjoying a rare extended stint on Australian soil.
"The last few weeks are actually the most time I've spent in Australia for about 10 years, and the one plus in all of this is that it's really nice to be home," he said.
"You wish it was for better reasons and it sucks not riding but there's a positive to take out of it, for sure.
"I've kept pretty quiet and have been tinkering away on some bikes in the shed to keep myself busy, to be honest."
He added that he's had contact with the Pramac squad in Italy, as the country continues to be battered by the coronavirus pandemic.
"I've spoken to [team boss] Paulo Campinoti and my crew chief to make sure they're all okay," he said.
"Italy has been one of the hardest countries hit by all of this so it's hard to not to think of the team, I really feel for those guys. It's definitely not looking good with Italy.
"Being down here… for once the isolation of Australia has helped us so far and I'm hoping we don't end up as bad as a lot of places we're hearing about."
Conceding his own frustrations at not being able to compete, Miller also expressed sympathy with MotoGP fans around the world.
"There's so many people in so many places that love MotoGP and they'll be missing it," he said.
"Anyone who likes sport – and I count myself in that category as I love sport too – it’s hard when everything you get so much enjoyment out of gets shut down. You don't realise how much you rely on sport as an escape, something to get passionate about, how much you take it for granted until it's not there.
"Believe me, I know. It sucks, but we'll be back."