Any guesses how many times you can run up and down Arthur’s Seat in 24 hours?
Well why not ask Dave Bell, who has taken part in this crazy challenge with friends twice now?
The first time was in 2007, but last year he watched his friend hike up and down Edinburgh’s most famous rocky mountain 41 times in one day.
But more was achieved because of that event other than aching muscles and sleep deprivation.
“It was after that myself and Meredith Adams, who was also taking part and who also has a love of outdoor challenges, decided that we could develop a series of novel endurance events dedicated to social engagement,” said Dave.
Backed by environmentally-minded young people, MAD (Move Act Do) Challenges was born with the aim of offering innovative and inclusive physical challenges in Scotland.
Its core ambition is to connect people to their environment for both individual health benefits as well as encouraging sustainable behaviours within the local community.
So it’s fitting that the first event - MAD Clyde - is taking place on Earth Day on April 22, starting off from one of the central belt’s most beautiful places.
The MAD Clyde event will run from the Falls of Clyde in New Lanark all the way along the Clyde River into Glasgow, finishing just outside the SECC.
For those wishing to go the whole hog - known as the MAD Masters - that will mean a 35-mile weighted trek along the Clyde Walkway within 12 hours.
Others looking to do a little less - MAD Movers and MAD Starters - can join the route at Strathclyde Park or Cambuslang.
Those taking part are looking for sponsorship, but their supporters won’t need their bank cards and won’t need to log on to Justgiving.
Instead, participants are looking for friends and family to commit to a sustainable behaviour change - like using recyclable cups or cycling to work.
To do this, MAD Challenges are using Do Nation, a digital platform to help people live happier, healthier more sustainable lifestyles.
Dave said: “This isn’t about pushing the green agenda down people’s throats, it’s about doing something that will directly benefit, you, your family or your area.
“Pledges that people make as sponsorship for those challenges could also save them money, or improve their health as well as making their lives more sustainable.”
The creation of MAD challenges also marks the first time that a whole series of events has been organised to solely support Do Nation.
And to celebrate that landmark, Do Nation’s founder and director, Hermione Taylor will be taking part in the Clyde Walkway challenge.
Hermione, who will travel from London for the event said: “This is a real milestone for us.
“Holding an event series that was entirely for Do Nation has been a dream of mine but we have never had the resources.
“So I think it’s really awesome that MAD Challenges are doing this.
“I was originally going to do the whole 35 miles, but I have downgraded a little to start closer to Glasgow so we’ll see how it goes!
“So far, the pledges MAD Challenges participants have raised could save as much carbon as 15 flights from Glasgow to Amsterdam - but I’m sure that will increase a lot over the coming weeks.”
Those behind MAD Challenges can’t wait for the April 22 event, and hope that it will be a fun challenge for all.
Dave, who is based in Edinburgh and who works for SEPA said: “The company William Tracey has donated empty two litres plastic bottles which we’ll fill with water from the River Clyde. We’ll give three bottles to each of the participants to carry along the walkway and this will provide the weighted element.
“Those bottles can then be reused or recycled.
“I really hope lots of people will sign up for this event.
“It’s an opportunity to push yourself in a way that’s different from other challenges, and receive sponsorship from friends and colleagues in a different way.”
Dave added: “Through MAD Challenges, people can reduce their negative impact on the environment, but we want to go further.
“Through our events, we hope to make people aware of not only reducing their negative impact but, beyond that, look at what they can do to impact positive change.”
To find out more or to take part visit www.MoveActDo.com, follow @mad_challenges or log onto facebook.com/MoveActDo.