Sam Wheeler, 34, from Portsmouth, works at Workshop Recruitment in Drayton and is hoping to raise £3,500 for Brain Tumour Research.
Sam’s colleague and close friend Joan Cook died in October age 67, just four months after her diagnosis.
The speed at which Joan became ill was a huge shock to the team at Workshop Recruitment.
Sam said: ‘Joan was a very positive and focused lady and her generous and bubbly personality meant she got on extremely well with everyone.
‘Even when she became ill, she was determined to live life as normally as she could, despite undergoing radiotherapy treatment.
‘She never gave up and was working until the week before she died.’
Outside of work, Joan and Sam shared a love of baking, often exchanging recipes and tips.
She had even offered to make Sam’s wedding cake, with him set to marry his girlfriend in March.
He said: ‘Joan’s bravery, fight and never-give-up attitude has inspired me to enter the London Marathon in her memory to support Brain Tumour Research.
‘I want to do all I can to raise awareness and urge people to donate to this great cause. One of our directors, Peter Hunt, also lost his mother to a brain tumour four years ago, so this a cause which is very dear to all our hearts.
‘Very little is known about the causes of brain tumours so it’s vital that we raise as much money as possible to fund further research and hopefully bring an end to this awful disease.’
To support Sam, go to uk.virginmoneygiving.com/SamWheelerRunningForJoan.