We talk about a career path, but my life in movies is nothing like a path.

It's more like that spidery fairground ride that hurls you outwards, away from the centre, then inwards, spinning as you go. I'm always dashing, in different directions, around movies. In my twenties I made documentaries for TV. Then I switched direction and became director of the Edinburgh International Film Festival. Then I changed again, to become a film critic and TV presenter. Then I wrote books on cinema, taught at universities, and curated things about children and cinema.

During these years – the 1990s and 2000s – cinema itself was undergoing a digital revolution of dizzying speed. It was a fascinating cyclorama. But instead of trying to get off the funfair ride and take stock of all these technological, industrial and personal changes, I stayed on it and spun some more.

Three years ago, at the age of 43, I started again. I made my first film for the big screen – The First Movie, in which I filmed Kurdish Iraqi kids learning to make movies. Then I made a second cinema film, the 15-hour The Story Of Film: An Odyssey. This late start as a cinema director meant that these films had the themes and feelings of middle age. They were elegies for youth and the movies. I'd lived enough to put a certain amount of wisdom into them. They travelled the world, played in big festivals such as Berlin and Toronto, in the Museum of Modern Art in New York, and the Ullens art centre in Beijing. And the reviews! Critics described my work the way I described Terrence Malick's. I blushed. I had arrived. Again.

In such a lucky position, you'd perhaps expect me to try to make a more mature film still, perhaps starring some of the actors that I've come to know. You'd maybe guess that I'd polish my work, or use fancier camera equipment, or adapt a novel for the screen, or move to London or LA. But I've done something like the opposite of these things. I've gone smaller, grungier.

I've just completed a movie, What Is This Film Called Love?, which was made like a 20-year-old might make a film, like Mike Skinner of The Streets made his first solo album. It's lo-fi, bedroom art. Amateur. Shot for a tenner. Experimental like first films often are, adolescently in love with shots and cuts. Stuffed – overstuffed – with influences and thoughts, like a film made in the 1920s, when cinema was still young. Plus it's about me, so it's self-centred too, a classic trope of young work. Instead of taking stock, or moving forwards in a career path kind of way, I've jumped backwards.

What Is This Film Called Love? was shot in three days, in Mexico City, without a budget, crew, script, schedule, equipment or even a plan to shoot anything. I was supposed to do nothing for three days but, instead, I walked for 45 miles, imagining that I was chatting to the great director Sergei Eisenstein, who had some of his best ideas about happiness and art in Mexico in the 1930s. I filmed the city, myself, kids, animals and street life. I lay in bed, got drunk, listened to music, and filmed the whole shebang.

When I got home, my editor Timo Langer cut it, we sent the rough cut to two great musicians, PJ Harvey and Simon Fisher Turner. They said nice things about it, and allowed us to use some of their music (Simon Fisher Turner composed some of his with Espen Jorgensen). What Is This Film Called Love? was suddenly a living thing. It became more musical, more tenebrious. We sent the rough cut to some festivals. They accepted it, and it gets its world premiere at the Edinburgh International Film Festival this month. I sent it to painter Alison Watt who, one day in Edinburgh, recorded the female voice in the film and gave it all sorts of emotions. So, within a month, improv, a movie ad-lib had become something. A young film made by a middle-aged jack-of-all-movie-trades.

The questions, I guess, are why, as a movie-world "insider", I've made a punky outsider thing and why, as I approach 50, I've made a youngish film. Is this just another birl of the fairground ride? Another reset?

There are seven answers to these questions and, I realise, writing about them here is a kind of taking stock. The first is a biggie. Film technology and history now allow anyone to make small, intimate movies. The camera I used cost a hundred quid. If I'd been born a generation earlier, the chances are that I wouldn't have gotten within smelling distance of filmmaking. But now – ya beauty! – the most popular art has become among the most meritocratic of the arts.

The second reason is that, after decades in film, I now have the confidence to make something amateur. I no longer feel the need to look or sound professional. And nor am I afraid of making something with nakedly personal emotions in it.

The third reason why I've changed tack is that over the years I've gathered notebooks full of ideas and influences and never quite known what to do with them. In music it's cool to talk about the bands you listen to, but in film people often hide that kind of thing in order, maybe, to make their work seem more original. This is wrong, and so I am happy to admit that my film is full of the influence of Virginia Woolf, Sergei Eisenstein, Norman MacCaig, Frank O'Hara, PJ Harvey, Simon Fisher Turner and Joan Didion. Quite a brew!

The fourth reason why I've done this thing is that I'm a bit of an adrenalin junkie. I'm scared to think of how people will react to What Is This Film Called Love? (I'm expecting two-star reviews) and this fear is exciting, like a fairground ride.

The fifth reason is another biggie. I know the production pitfalls. I've seen so many friends spend a decade or more trying to get their film made. In the process they have kids, grow old, cry into their drink, doubt their talent and rail against the system. With this film, I simply ignored the system.

The sixth reason is that I've been writing a book called Rupture, in which I try to look at why someone might jump to a completely new career half way through their life, not because they're disliking their current job but because there's so much else to do. My new film is a kind of jump.

The seventh reason is that after making The Story Of Film: An Odyssey for almost six years, I wanted to do something that is less content-driven, more about the pleasures of shot and cuts, combining image and music. In other words, it is more free. And as I type the word "free", I realise that all the changes that are happening in movies and me are somehow about freedom. The miniaturisation of cameras frees us to run around with them. Not working in the conventional film industry way has freed me up to film anywhere and anytime I like.

What Is This Film Called Love? is about being free from work, free to walk for days in the biggest city in the Western world. Even its website is more open than most, as we've scanned the 90 A6 post cards on which I scribbled my ideas for the movie and which we used to edit the film, so when people have seen it, they can then go back and see where it came from.

So, my work life so far has been a zig-zaggy fairground ride. I suspect that the work lives of many others have been too. Maybe there are few straight career paths these days. Maybe careers have a beginning, middle and end, but not necessarily in that order.

What Is This Film Called Love? has its world premiere at Filmhouse, Edinburgh on June 26, 6pm as part of the Edinburgh International Film Festival; it has a further screening at Cineworld, Edinburgh on June 30, 7.45pm, http://whatisthisfilmcallledlove.co.uk. Follow Mark Cousins on Twitter at @markcousinsfilm