Ever wanted to quit halfway through a workout? Is the motivation there but your body is telling you to stop?
Six years ago, ultra-runner Grant MacDonald was training when a sudden "blinding" headache stopped him in his tracks.
Deciding to call it a day and head home, MacDonald was found clutching a speed camera on the road by a passer-by who realised he needed urgent medical attention.
"My head had burst and I was having a brain haemorrhage," MacDonald tells BBC Scotland.
The biomedical scientist suffered a subarachnoid haemorrhage - an uncommon type of stroke caused by bleeding on the surface of the brain - while running in 2014.
Approximately three in five people who have this type of haemorrhage die within two weeks, and half of those who survive are left with severe brain damage and disability.
"I was lucky to make a complete recovery," MacDonald says. "So many people die with a condition like I had, so everything after is a bonus."
Recovery was a slow, steady pace and it took him a year to get back to his previous standard.
"I had my first run at day 37 after my brain haemorrhage. It was more of a walk than a run. It felt like going back to square one and learning how to run all over again.
"I was off work for months and running was a way of staying focused."
'You run for 24 hours & eat on move'
MacDonald joined the Bellahouston Road Runners in Glasgow 11 years ago in an attempt to get fit. Starting with park runs and progressing to ultra marathons, the 41-year-old now runs for Garscube Harriers and has represented Great Britain. He found his passion in 24-hour ultra-running.
"It's quite a niche sport, even among ultra-runners, a lot of them think 24-hour running is weird," he says.
"It's usually run on a track or a 1km loop and you start at midday and continue running for 24 hours to try and lap up the most distance that you can in that time.
"You can stop and leave the track then come back on, but the only way to really do well is to keep running for the entire 24 hours, eat on the move and never stop.
"For me, it's an incredibly pure score. It's how far can you push yourself mentally and physically. You just go in to your own little world and nothing else matters."
Having completed multiple 24-hour races, MacDonald is aware that the extreme nature of them takes its toll and he will need to hang up his trainers someday.
"I am convinced you have only got about seven or eight 24-hour races in you before your body just gives up. I have done seven now and I am still desperate for my next one."
'I'll be really fit with nothing to do'
With the temporary halt of everyday life due to the coronavirus outbreak, MacDonald has had to "get creative" with his training routine to ensure he stays in peak physical condition.
"I do a lot of my training by running to and from work - 10 miles each way daily - which takes me about an hour and half if I am taking my time. I also usually do a five-hour run on a Saturday.
"We are only supposed to go out to exercise for one hour per day now. So I have adapted my routine with lots of yoga, strength and conditioning classes in the garden and one long run a day."
His next 24-hour race is scheduled to take place in Verona, Italy - one of the countries most affected by coronavirus - in September.
"I can't see it happening this year, but we have to train as if it is going ahead. If it doesn't then we'll just be really fit with nothing to do!"