I'm fond of roundabouts, and on the first day of my travels after standing for three hours struggling to thumb a lift, I realised that I was going to be spending a lot more time with them than ever before. And so to Rhyl, a desolate seaside town in north Wales. I could handle being ignored by driver after driver; that was fine. But I wasn't prepared for the sheer animosity of the lads in souped-up cars who leaned out of windows to tell me to "Fuck off"; and when two pretty women pointed and burst out laughing, I realised that I had reached a whole new plateau of awfulness. This, I thought, is possibly the most dispiriting experience of my life.

How had it come to this? The plan had been so simple. I was going to hitchhike round Britain for a month or so and make a documentary about the people who picked me up. There were just two rules: I would accept every lift I was offered; and I would go wherever the drivers took me. I'd always wanted to make a British road movie. There's something about the blandness of the British landscape - all those dual-carriageways, Travelodges and power stations - which I find very appealing. I also suspected that the majority of my rides would be from single men with whom conversation would turn naturally to my current obsessions: masculinity and loneliness.

I went into making the film with some apprehension. I was convinced that I would be attacked by a madman or picked up by some pervy couple who would force me at knife-point to go dogging. That didn't happen. But what I hadn't considered was that there are very few hitchhikers on the roads any more and therefore my chances of getting a ride seemed slim. My growing sense of gloom was not helped by the Belgian hippy I met in Holyhead who told me: "Hitchhiking in western Europe is dead."

Actually, I averaged about four lifts a day and people went out of their way to help me. Some went miles off their routes to find me a place to spend the night. Others offered me cigarettes and coffee. In the end, I finished my travels feeling more optimistic about humanity than I had for years.

Phil
10.30am: Penrith to Hamilton Services, M74

A high proportion of the people who stopped for me were ex-army. The first thing I wanted to know from Phil, who had served as an NCO for 22 years, was: what is it with ex-military and hitchhikers?

He said it was something about a sense of duty - one should pick up hitchhikers - but more importantly, it was about comradeship, the feeling that, as a society, we were all in it together. When he was courting his wife 32 years ago, he hitched every week across the country to meet her and he has picked up hitchhikers ever since.

Phil is happily married. He puts the secret of his happiness down to the fact that he leads what he calls "an average life". People can be divided into three categories, he says. There are the people at the top of the pile with outstanding talents and there are the people on the bottom, who achieve nothing. Both these groups will find it extremely difficult to find happiness. It is the people in the middle, such as himself, who have "average lives" and are "nothing exceptional" who stand the best chance in this world.

David
11.30am: Rhyl to Holyhead

David lives on his own in a small Welsh town. He has no friends or family and feels completely cut off from the world. His only company is two dogs, which he takes everywhere. Sometimes, on a summer's day, he likes to drive up and down the coast road for hours - just taking in the scenery, looking at the mountains and the sea. He rarely speaks to anyone, so it was a relief for him to talk.

Pan-pipe music was playing in the car. This was important to him; it was his "lady friend's" favourite music. She had died two years ago and since then his life had fallen to pieces. His depression makes him unable to work; he cannot sleep without sleeping pills.

He dropped me off at a garage. Two hours later, he picked me up again - I was still at the side of the road - and we resumed our conversation. It was then that he told me his girlfriend had committed suicide and had died in his arms. He had never really told anyone this before, but, as he said, sometimes it's easier to talk to strangers.

X
8pm: M42 near Redditch to Welshpool

(X does not want his name or picture in this article because he believes that "relating to God as a person is more important than relating to a picture of a person".)

X had seen me an hour before as he drove past. Hitchhikers are a rare sight, so he said to God, "I wonder if he'll be there when I come back." When I was, he realised it was a sign to pick me up.

There was something very intense about his face and I wanted to film him from the moment I got into the car, but he was unsure. He needed time to think it over. After a long pause, he said, "I'll talk to you because it reflects God's glory."

X suffers from psychosis, had a breakdown and was institutionalised. The doctors said he would be on medication for the rest of his life. But one day, God spoke and told him that he was cured. X stopped his drugs and is yet to suffer a relapse. Even his doctors thought it was a miracle.

It was dusk when he dropped me off in a small west country town. As I filmed him driving into the distance, church bells were faintly ringing.

Trevor
11.45am: Welshpool to Wolverhampton

Trevor, a lorry driver, has spent years tramping up and down the country's motorways, but now he wants out. Trevor spends five days a week away from home; it has caused havoc with his marriage. A couple of years ago, he got a call from another driver informing him that his wife had moved out and had taken their child with her. Trevor immediately turned round and drove home. Without warning, she had run off with a guy she had met over the internet and had taken everything. The house had been stripped, the bank account emptied - and all that was left was £40 on the kitchen table and a note accusing him of selfishness.

Trevor was consoled by his neighbour, the girl next door, and they are now a couple. The last thing he wants is for history to repeat itself, so he and his girlfriend are hoping to chuck it all in and open a cattery together.

Robert
2pm: Glasgow to Edinburgh

Robert is a struggling alcoholic. When I met him, he was going from Glasgow to Edinburgh to visit an old girlfriend. Past experience had shown that he often ends up drunk when they get together, but this time he is determined to stay sober. He usually travels by bus but today he is taking the car in the hope that it will help him stay off the liquor.

Robert's drinking has affected his relationships with everyone close to him. He feels that his friends and family have been supporting him his whole life. Recently, he helped out with a charity single on which Shane MacGowan played as a way of giving something back. The charity, which helps people suffering from motor neurone disease, is one he feels passionate about. In fact, he only agreed to be filmed if I mentioned it.

When I spoke to him the other day, he was still battling with his drinking, but he hasn't given up the fight.

Peter
3.10pm: Bristol to Strensham Services, M5

All my laundry had just been stolen from a laundrette, so I was not in the best of moods as I struggled to hitchhike out of Bristol. Peter changed all that. He's in his mid-50s, has a thick Gloucestershire accent and was driving a small truck wearing only boxer shorts. He still lives with his mother. She is an invalid who needs 24-hour care.

As we drove down the M5 in the oppressive heat, he told me that he was fed up with being single - the loneliness was crushing. He had tried everything: friends of friends; personal columns; dating agencies - but with no success. At the end of his tether, he had recently forked out a lot of money on a singles holiday in Cyprus. And there he had met a woman, a teacher from Surrey. He had bought her a handbag and she had given him a kiss and a hug. They had exchanged numbers. He hasn't called her yet, but when he summons up the courage, he is hoping that his search will be over.

· Where Are You Going? is on Channel 4 tomorrow night at 12.30am. If John, a lorry driver from the north-west, sees this article and wants to get in touch, email jasonmassot@yahoo.co.uk