Prince Harry has wished fundraisers taking part in a 100km walking challenge "good luck", encouraging them to "dig deep, physically and emotionally".
The Duke of Sussex, who served alongside Gurkhas in Afghanistan, was speaking ahead of The Trailwalker Relay, which has been organised to support The Gurkha Welfare Trust and Oxfam.
"Thank you for stepping up for the Gurkhas, for Nepal and for all the communities impacted by this pandemic," Harry said in his video message.
"Doing this relay virtually is going to make it even more difficult than it already was, so you're going to need to dig deep, physically and emotionally, to get you and your team across those 100 kilometres.
"I know that you can do it and with every step you take just remember you're helping those who need it most."
The event usually involves hundreds of civilians walking across the South Downs alongside the Queen's Gurkha Signals.
But this year's mass walk was cancelled, with people now taking part separately in a virtual event, splitting the distance between teams while following social distancing guidelines.
Today is the start of @TrailwalkerUK Relay 2020!— Gurkha Welfare Trust (@gwtorg) September 21, 2020
Prince Harry has wished all the participants good luck in their gruelling challenge.
Since he was a child, Harry has an amazing history with both the Gurkhas and our charity. pic.twitter.com/VK36VjElFm
Prince Harry mentioned his experience with the Gurkhas, including his visit to Nepal in 2016 following the devastating earthquake.
"With COVID-19, the world is being pitted against a new challenge, one that is devastating and destructive in its own right," the duke added.
"I am heartened to see that once again, the Nepalese spirit is unwavering.
"In Afghanistan, I was honoured to serve alongside the Royal Gurkha Rifles. These soldiers showed me what they believe in.
The Trailwalker Relay will take place until 27 September, with money raised from the ven supporting the work of Oxfam and The Gurkha Welfare Trust.
The latter has been supporting Gurkha veterans and their communities in Nepal during the coronavirus outbreak by distributing aid.
Oxfam has been supporting vulnerable communities through the pandemic, reaching over four million people in 62 countries.
Cover image: Prince Harry photographed earlier this year (Picture: PA).