Dommy Szymanska, 25, lost her grandfather to a heart attack three years ago and decided to complete the 26.2-mile run for him and to raise money to help anyone suffering with heart problems.
The payroll administrator at the University of London aims to raise £2,000 for the charity and is just over a tenth of the way to her target.
She said: “I've wanted to do something in memory of my grandfather as well as raising money for charity and running the marathon has always been on my bucket list so it makes sense to combine the two.
"The marathon is one of the biggest events in London and is a great opportunity to raise money for a fantastic charity.
“I've always wanted to get into running but never have, although I think I've caught the running bug through all my training.
“If I was going to do another marathon, I'd love for it to be abroad. Maybe Berlin or Copenhagen, but I need to finish this one first!”
Gold, silver and bronze targets
Dommy still needs to raise almost £1,800 before she competes, but thinks this is a very achievable target and has a number of events in the pipework.
“First up I have a Valentine's event on Saturday (February 13), all my friends and family have bought tickets and local businesses have donated raffle prizes so I am hoping it will be a successful night.
“I've also got a cake sale planned and I'm going to organise a film night which should push me towards my fundraising target.
“I still have plenty of time until the race so I'm confident I will reach my target and hopefully go past it.”
Dommy has made an impressive start to her training, currently running between 20 and 25km, just over half the full marathon distance.
She said: “My main aim is to finish under five hours. Although, I've set myself a gold, silver and bronze target.
“I'll need to finish under four and a half hours for gold, four and three quarters for silver and then five is the bronze.”
Dommy will be running the London Marathon on April 26.
If you would like to sponsor her to raise money for the British Heart Foundation, visit her just her JustGiving page.