Fitness coach Sophie Holmes, 32, set the record by completing the Edinburgh Marathon.
Sophie, who has cystic fibrosis, has now raised £25,000 from the challenge which started with the London Marathon.
She is the first person with the disease to do 36 marathons in 36 days.
Cystic fibrosis causes mucus in the lungs and, at age four months, doctors said Sophie, from Southend, Essex, would not live past 16.
She said: “My determination to survive and thrive and to defy the odds has been born probably from as young as I can remember.
“When I turned 19, I was unfortunately told I only had two years to live.
“But, the naïve 19 year old me was not going to let that happen.
“So I started chasing after these big goals.
“When I then started to get better, they were like, maybe you won’t make 30.
“So when I turned 30, I decided I wanted to celebrate by running 30 marathons in 30 days.
“But at the time, we were in lockdown, so it wasn’t something that was possible.”
She continued: “Last year I got in to London for this year, and the Edinburgh Marathon and the idea was reborn because I was like, ‘I wonder how many days are in between both of these races?’
“I first calculated it as 35.
“So I started telling everyone that I was going to run 35 marathons in 35 days and then my coach recounted the days and said, ‘well, actually we are going be running 36.'”