Harriet Frost: 2x Arc of Attrition 100 mile finisher, Race Director, Business Owner of Grit Culture, Co-parent of Sea+Flo supporting people to upgrade their periods.

Tough Girl Podcast

Harriet Frost is a force of energy, endurance, and entrepreneurial grit.

From completing the notorious Arc of Attrition 100-mile ultra twice, to directing multiple trail races, to co-founding a menstrual cup company focused on sustainable period care for athletes — Harriet is redefining what it means to pursue hard things, in business and on the trail.

In this episode, Harriet shares her journey from growing up in Cornwall to discovering a love of endurance sport later in life — despite hating running at first. With no formal coaching, she’s built her own training strategy based on experience, discipline, and gut instinct — and it’s taken her to the finish lines of some of the UK’s most brutal ultra events.

We also dive into the founding of Sea+Flo, a period care company created by women, for women, aiming to empower people to better understand and manage their menstrual health during sport. Harriet speaks candidly about the mental strength required to train alone, run in the dark, and manage periods while racing, as well as her mission to bring more female voices to the forefront of adventure and endurance media.

This is a conversation about grit, vulnerability, and showing up — again and again — even when the path ahead is long, muddy, and uncertain.

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Show notes

• Who is Harriet?
• Completing her 2nd Arc of Attrition 100 mile ultra
• Race Director to 2 current races and soon to be a 3rd
• Running her own business called, Grit Culture - focused on business management
• Launching a menstrual cup company called Sea+Flo in 2024 with her best friend
• Dog mum to November
• Being surrounded by an amazing network of friends and family
• How things connect together
• Speaking with Harriet mum, Theresa Frost on the Tough Girl Podcast
• Having parents to everyone
• Childhood and growing up in Cornwall
• Learning resilience and grit from a young age
• Being supported by her parents
• Loving school and heading off to University in Southhampton to study fashion and journalism
• Not really knowing what she wanted to do
• Travelling and working on super yachts
• Heading off to London for 3 years
• Spending time in Australia for 2 years, and New Zealand for 2 years, before moving back to Cornwall
• Hating running…. And finding running really hard
• Living in London and doing her first triathlon in 2012/2013
• Doing her first marathon during her first 100k
• Race to the Stones 2017
• Doing her next ultra in 2023 - Isle of Wight in April
• Arc of Attrition on the South West Coast Path. 100 miles.
• Entering the race
• The Plague 64 miles race (toughest races she’s ever done)
• Planning her own training and talking things through with her mum
• Going on how her body feels and past experience
• Working backwards from the race start date
• Focusing on back to back runs
• The mental toughness of training and training solo
• Out and back runs and the mental challenge
• Knowing there is still more in her
• Fitting running into her life
• Training in winter and in the dark
• The stress of running in the dark as a female and the wasted energy
• Why it’s discipline over motivation
• Recovery…. And what it looks like
• Having big toe strain
• Why the Arc was different in 2025 after being taken over by UTMB
• Feet and blisters
• Nutrition, food, fuelling
• The struggle of eating food
• Practicing eating on 20 milers
• Training and periods
• Sea + Flo reusable menstrual cup company
• Which menstrual cup?
• How using a menstrual cup came about
• Putting herself out there a bit more
• Women doing amazing things and not getting enough airtime
• Nikki Love breaking the women’s record for running across Australia
• “It’s not about beating the men it’s about winning for the women” - Hannah Paradise
• Jasmine Harrison - swimming the length of Great Britain and not being able to to get a book deal -
• The lack of stories of women in the news
• The women who inspire Harriet
• Lucy Gossage - “It’s a privilege to choose to suffer”
• How to connect with Harriet online
• Final words of advice for women who want to pursue endurance sports
• Being inspired by Sarah Wilson
• Building your resilience in sport or physical challenges and how it can help you in your everyday lives

Social Media

Website

grit-culture.com

seaandflo.com

Instagram

@harriet__frost @grit.culture @seaandflo