That is the challenge double leg amputee David Williamson has set himself.
The 40-year-old from Portsmouth is determined to complete the challenge which begins on June 14 and will see him complete a marathon a day at tracks around London before the final event at Stoke Mandeville Stadium.
He said: ‘Growing up I was never clever enough to be a doctor or a scientist but I knew I wanted to be in a profession like that where I could help people.
‘I love sport and doing crazy challenges is the best way I know how.’
Three-year-old Felicity Gooderham from Portsmouth is one of the people David is helping and will receive a third of the money raised.
She has undiagnosed genetic conditions which doctors think causes her three different brain conditions. The youngster is visually impaired, has epilepsy and needs 24-hour care.
David said: ‘I have raised money for Felicity before when I did the Brighton Marathon a few years ago. My step-mum knew her great-grandmother through the WI and when I found out about her condition I decided I wanted to support her and her family.’
Felicity’s mum Sarah said: ‘What David is doing is absolutely amazing and the money will go a long way with helping us to adapt our home for Felicity and get vital equipment.
‘He is so incredible and generous as this is the second time he has helped our family. We are so grateful.’
Another recipient of David’s #30in30 challenge is four-year-old Emerson who developed a cyst on his spine when he was two years old and has left him paralysed from the waist down.
David said: ‘Emerson’s father contacted me on Facebook after I received a We Can Do It award from The News and told me my story had given his family hope for their son.
‘I sent the WCDI to Emerson and wrote him a letter asking him to look after it for me until he could overcome his challenges and win won himself. It is humbling to know that the things I do have some effect outside my little circle.’
Both Felicity and Emerson will join David on the last lap of his last marathon.
To give back to the people who inspired him into sports when he was younger, a chunk of the money will be going to charity Limb Power which encourages and supports amputees and individuals with limb impairments in physical activity, sport and the arts to improve quality of life and to aid lifelong rehabilitation.
David added: ‘I loved sport growing up and went to lots of sport disability weekends in Gosport but I fell out of love with it in my 20s.
‘Limb Power helped me to get back into it and I really wanted to give something back as a thank you from myself but also to help youngsters and people in the future who may need their help.’
For training David has been making sure to get out every day and makes himself get off the bus a few stops before his.
He said: ‘It sounds silly but four or five stops before mine really helps especially as I am really rubbish with training and keeping to a schedule.
‘I am not nervous for the actual marathons but I am nervous of failing as I want to succeed for Felicity, Emerson, Limb Power and for everyone who has been working behind the scenes to help me get ready for what is undoubtedly my craziest challenge yet.’
To donate to David’s cause visit justgiving.com/fundraising/dw30in30