A woman will set off on a four-year 20,000-mile (32,000km) trek around the coastline of the UK and Ireland.
Karen Penny has been sleeping in her back garden and walking daily to prepare for the mammoth challenge.
The 53-year-old will take a lightweight tent – but her backpack will weigh about 17kg (37lb) as she carries essentials such as a sleeping bag, water, clothing and protein bars.
“I know I can take it in my stride,” said the mother-of-one from Swansea.
Ms Penny, who walked from John O’Groats to Land’s End last year believes she will become the first woman to complete the coastline walk continuously.
Her adventure is started on Monday when children at Pennard Primary School, Southgate, Swansea, waved her off at 09:00 GMT.
And she has vowed not to come home until she has completed her challenge, which she hopes to be complete by January 2023.
Her aim is walk 15 miles (24km) a day and raise money for Alzheimer’s Research UK.
“Both of my husband’s parents died from dementia-related illnesses and it had a massive effect on me,” said Ms Penny, who was in the legal profession for 30 years before retiring.
“With Alzheimers, it just keeps getting worse and you see people who you love and care about deteriorating in front of your eyes. I just want to try and do something to help.”
Husband Mark Faulkner, a retired police officer, will meet her in a camper van every six weeks – giving her somewhere to sleep and to replenish and replace supplies.
“I think it’s awesome,” he said. “I know she can do it.”
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