A former hill walker who has multiple sclerosis (MS) is aiming to reach the summit of Snowdon, carried in a wheelchair by a team of supporters.
Martin Williams, 52, of Cardiff, is undertaking the challenge 15 years after being diagnosed with the disabling neurological condition.
He said he was determined to show his disability was no bar to the outdoors, including Wales' highest mountain.
He also hopes to raise funds for a charity that provides disability care.
"I'm just looking to carry on what I did before MS," said Mr Williams, who now lives at the Leonard Cheshire home, Dan y Bryn in Radyr.
"I want to break down the barriers for people like myself.
"I'm now in a wheelchair - but apart from that, I won't let MS change me."
Mr Williams said the idea of reaching the summit of Snowdon came from his wish to complete the three peaks challenge of climbing Snowdon, Ben Nevis and Scafell Pike, the three highest mountains in the UK.
"My friends and family told me: 'Let's try one thing at a time' - so Snowdon it was," he added.
"Hopefully there will be more to follow."
Mr Williams said he and a team of around 16 supporters, including his two eldest sons, Daniel, 28, and Richard, 25, will help carry him up the Llanberis path route to the Snowdon summit.
They wre setting off at about 0800 BST on Saturday, and expect the it take about eight hours.
Money raised through the ascent will go towards helping fund assistive technology, such as electric door openers, at the Dan y Bryn centre that is now Mr William's home.
Meanwhile as his challenge got under way, another Welsh fundraiser was setting off to the summit of Snowdon in a bid to raise £10,000 for the campaign Beating Bowel Cancer.
Dafydd Jones, 27 and originally from Porthmadog, Gwynedd, was diagnosed with the disease in October last year.
As well as climbing Snowdon, he will tackle Ben Nevis in September.
"I am taking on this challenge to raise awareness of bowel cancer and its symptoms as it's a disease that really can affect anyone," he said.
"I also want to show people that, no matter what you go through, you should live your life to the max.
"I hope that my fundraising and passion to make a difference will inspire others to do the same. Anything is possible if you focus and put your mind to it."