With the London marathon just two weeks away, we speak to Ollie Proudlock - who finished the 26.2 mile course in an impressive 3:04:38 last year - about the challenge and his top tips for race day.
Ollie - who ran to raise money for the British Heart Foundation - says: "I have a history of heart conditions in my family.
"My grandmother died from a ruptured aorta, my uncle had a double bypass, and my dad was diagnosed with a weak heart muscle in 2006 and told he had come dangerously close to having a heart attack.
"So running for the British Heart Foundation was a huge honour. My goal was to get under four hours, I couldn't believe when I looked at the timer at was closer to getting under three hours!"
And Ollie says his best advice for race day is a good night's sleep and a carby meal.
He adds: "Make sure you are completely rested, I was so nervous the day before but I forced myself to go to bed early.
"I also had spag bol for dinner to carb load, as well as porridge in the morning and a banana. Nutrition is definitely key to having a good race, but don't use energy gels unless you've trained with them because they can upset your stomach!
"Most importantly try to enjoy the day! The crowds are amazing and they really push you along the course, it's an incredible feeling."
If you aren't quite up to taking on a marathon, why not sign up to one of the British Heart Foundation running series events by clicking here.