Mr Wheeler is busier than ever, focusing on painting from the countless, mainly ballpoint, drawings he has done over many years.
"I know time must be limited . . . of the very nature of things, you can't last forever. I've got so much to do I can't possibly see enough time ahead of me to get through all this," he said.
An early riser - "there's no chance of lying in here", his wife of 66 years, Phyllis, said - he was up about 7.15am and started painting after breakfast, finishing each night between 9.30pm and 10pm.
Mr Wheeler said he did not think about retirement - "you think in terms of the work you've got to do and whether you're going to have time to do it all" - and his interest was in producing a good job.
The Wheelers moved to Oamaru in the early 1950s when Mr Wheeler got a job as art master at Waitaki Boys High School.
He resigned after 18 years to concentrate on his series of books on sheep stations and to paint full-time.
The couple also maintain a large garden.
Mr Wheeler said he and his wife had always made a good team, right back to the days in Christchurch when they would go cycling in the countryside, with baskets on the front handlebars, so he could go drawing.
"We've always been on the go. It's stopped us being bored."
Mrs Wheeler was also a "wonderful" selector of subject matter for his paintings.
"She talks my language," he said.
Mr Wheeler is celebrating his birthday with a function for family and friends at The Homestead.
