Sir Christopher Ball, who celebrated his 90th birthday last month, will run and walk 10 kilometres at Brathay in Cumbria on 17 May. Sir Christopher is no stranger to running challenges, having completed 10 marathons in 10 days in his 70s.

Could you tell us why you first started supporting Autistica?

My wife and I adopted four children as babies and had two biological children. We adopted Peter, who became our 5th child. As he grew up, he behaved differently in those early years, and we realised he needed special care.

I happened to read about what was then called Asperger’s Syndrome and we subsequently found that Peter was autistic. At this point, we learned as much as we could about autism. Our other children noticed there were different rules for Peter, and we explained why.

When Peter grew up, he initially went to a special school before persuading us to enrol him in a mainstream school. He worked hard and was very good at physics and maths. When he was eight, he told me I was no longer a good enough chess opponent! We loved him enormously.

In his late 20s, he found work preparing food at an Oxford college. It was then that he developed epilepsy, which is quite common for autistic people. He died of a severe epileptic fit several years later.

I wanted to help autistic people. I began working with Autistica and doing what I could to support a broad range of charities focused on autism.

What inspired you to take on this challenge?
Predominantly my 90th birthday. I have been a fundraiser for a very long time, so, all going well, I plan to make my final charitable commitments a sponsored run in 2025 (at age 90), 2030 (at age 95), and 2035 (at age 100). My eldest daughter will be accompanying me to help make sure everything goes smoothly.

How has training been going?
Training is going well. My longest run in the lead-up to the 17th May has been 7 miles, so I’ve done the distance already. In the past, I’ve found that it’s really helpful to train by completing as close to the race distance as possible, so I know I can do it on the day. Psychology is everything.

I’m now ‘tapering’ off my runs, and will do a couple of shorter ones in the week before. I’ll be running more than walking on the day, but it will be a mix of both.

What makes Autistica an important charity to support?
In my view, it's the leading charity for assisting autistic people through research. Autistica helps develop better government policies and enables truly important research that brings about change and support for autistic people. I've worked with Autistica for several years and have huge admiration for the charity. I think everyone should know about their work and hopefully want to support it.

What advice do you have for people wanting to be as active as you in their 90s?
I’m a member of the Oxford Longevity Project, and when people ask me this, my response is: take your MEDs.

The ‘M’ stands for a positive Mindset. You can’t do everything you used to do, but this doesn’t stop you from making the best of the life you have. Don’t watch the news, appreciate nature, and recognise how vital your family and friends are; invest time in them.

‘E’ is for Exercise. I run every other day, and on my off days, I do a 40-minute indoor exercise regimen.

And the ‘D’ stands for Diet. I wholeheartedly recommend a plant-based diet, as vegan as you can manage. Get your food as naturally as possible. Cook at home and swap shop-bought foods for naturally grown food. Avoid alcohol and have a very moderate intake of sugar and salt.

And the small 's' of MEDs is to remind us to reduce and avoid stress, as far as possible.

Thank you, Sir Christopher, for your support and insights.