Exercise is increasingly being prescribed for people with depression, mental health campaigners have found.
By Caroline Parkinson
BBC News health reporter
Jamie feels his life is now much more balanced
Jamie Stevenson, 37, says getting active has helped him cope with the illness.
He first became ill seven years ago, when working 16-hour days as a journalist meant he stopped looking after himself.
"I couldn't maintain any balance between my home life and my emotional life because I was working such long hours and under a lot of pressure."
Initially, he did not seek any help but in 2002, he began to feel low again and couldn't even go to the supermarket.
"I became more withdrawn. My relationship broke down and I began living on my own.
"I didn't really want to leave the house."
Jamie started taking the antidepressant Seroxat, but found it made him feel "very sedated".
Changing to Effexor, another antidepressant, did help. "It put a stop to the slide".
But he felt it wasn't enough.
"I had to push myself to get out of the house."
'I made myself go'
Jamie then changed doctors - and his new GP happened to be a keen marathon runner.
"She told me to try exercise.
"Bit by bit, I started going walking; setting myself targets to try and get some basic exercise.
"Then I started to go to the gym. That was really difficult because I preferred to be by myself - and I had to go there in my gym clothes and be with muscly and toned people.
"But I made myself go in, and just used the machines.
"I remember the first time I came back from the gym I felt elated.
"It was the rush of endorphins, but also I had broken a taboo with myself. I could go out."
Jamie did maintain his gym visits for some time, but now gets his exercise from walking his dog every day.
He's on a mild dose of antidepressants, and has changed his job.
Jamie backs the exercise referral schemes. "There isn't one particular answer for people with mental health problems because it's down to what the individual needs, but I would recommend it to anyone.
"If you can push yourself, it's a first step and really does help."
Paul Fennel manages the Camden Active Health team in north London which offers eight-week programmes to people with many kinds of conditions - including those with mild and moderate depression.
"We often send them to sessions with a strong social element, such as badminton, but they can also go to the gym or to classes such as pilates or yoga.
"People with mental health problems can also be overweight or smoke, so that has to be considered when we are drawing up an exercise programme for them."
But he said the scheme did seem to help, with 80% completing the course.
"We get amazing feedback. People say things like 'it's transformed my life'."