ndy Field was midway through his standup run at this year's Edinburgh fringe when he was struck by an unusual urge – the urge to draw a horse. "I hadn't sat down to draw anything since I was at school," says the 34-year-old comedian. "Drawing was a skill I didn't have."

He's not lying. The subsequent horse Field posted to TikTok and Instagram was rather naive, with its four identical straight legs and cartoon eyeball. But the project he announced alongside it – Drawing a Horse Every Day Until I'm Really Good at Drawing Horses – immediately captured people's hearts. Over a million people watched the minute-long video of him drawing that first horse with a four-colour ballpoint pen. By day three – an undeniably terrible effort in which the horse appeared to have sprouted a platypus's bill – more than two million, by his estimation, had tuned in. "People were willing the series to continue," says Field. And so he did.

Field is now approaching day 80 of his horse drawing series and it's been quite a journey. We've had howling horses (day 67), an Ali-style boxing horse knocking out an equine Sonny Liston (day 58), a skateboarding horse (day 29), a horse turning the tables and drawing a portrait of Field (day 24), and a horse on its knees playing a guitar solo (day 21). If some commentators were hoping Field was going to draw the same horse every day and gradually work on his understanding of proportion and perspective then they were left disappointed. Because Field's project is really a joyful celebration of drawing for fun – of following a daft idea and seeing where it takes you.

Sometimes, that's not a place anyone intended. On day 48, Field decided to focus in on a horse's face, but ended up sketching something that – to his evident horror – became increasingly phallic. "I was picturing those shots in a Ren & Stimpy cartoon, where it's so grotesquely zoomed in and you're getting all the warts and sweat and veins. But I didn't draw a great shape of head, and, well …"

As part of his droll commentary on each day's effort, Field likes to name each horse. The one resembling male genitalia was given the moniker Gentle Brian. The guitar-shredding horse was Jimi Horsedrix. Often, the less traditional Field's horses are, the more impressive they turn out. He might have visited the National Gallery (day 19) to take tips from the master of horse drawing, George Stubbs, but he's more at home doing horses wearing shades (day 64) or horses infused with the spirit of his new kitten, Toast (day 56).

"I get dozens of comments every day with tips on how to draw horses – but if I sat down and felt as if I had to follow them it wouldn't have the same joie de vivre about it," he says. "Prioritise what brings you joy – and a horse playing an electric guitar brought me so much joy."

Field says that his love of horses started ironically: whenever someone asked what he wanted for his birthday, he would request a framed picture of a horse. "It was just a funny thing to ask for," he says. How many horse pictures did he receive? "Oh, a bunch."

This equine interest has undeniably served him well. The series has inspired some viewers to pick up a pen and draw their own horses, whereas some have said they watch each day with their children. "They've said it's a good example of someone not worrying about making mistakes and just enjoying themselves," he says. "That's been one of the most gratifying things."

Said parents are best advised to avoid day 69's image of horses observing oral sex. Field has also launched a merch range: the day three catastrophe makes an appearance on a T-shirt, as does his colourful swirl of horses eating each other (day 27, given the name Seabiscuits).

There have been notable landmarks. On day 50, Field redrew his first attempt, to show how far he's come. The difference was vast. "I now have a more segmented view of a horse," says Field. "I go through it, like, the ears are their own thing, then the little bit of hair between the ears that connects to the mane …." Many videos show his dedication to the curve that joins the neck with the front legs, a section of horse that Field refers to as "horse cleavage". "Don't even be gross," he says on one video. "It's a normal part of horses."

Field promised that, when he hit 100,000 followers, he would do an oil painting of a horse (Day 54), despite some viewers warning him off the idea. "They said it would be too messy," he says, "and they were right." But learning from mistakes is part of what Field is embracing. "What's the downside of doing a bad oil painting of a horse? I mean, it's not life or death, is it?"

Sticking to his promise of one horse per day hasn't always been easy. Soon after Edinburgh finished he spent a weekend at the End of the Road music festival on the Wiltshire-Dorset border, and was forced to film himself drawing from a windy campsite (days 14-16). "People were criticising me for not taking the pen off the paper – but I had to keep the pen down to stop the paper blowing away!"

It was at that festival that he saw one of his favourite bands, Geese, perform their song 100 Horses. Field thought that seemed like a decent number of horses to end his project on. "I have a plan for how I'm going to finish the series," he says. "Everyone in my life is telling me that it's a bit elaborate, but we've got to go out with a bang!"

The big question, though, as we head towards day 100: does Field think he will have made good on his desire to get "really good at drawing horses"?

"I mean … I almost regret calling the series that," he says with a laugh. "Because what's 'good'? To me, being good means being able to sit down and do art and feel fulfilled, regardless of the outcome. So in my head, I'm already good!"