A mental health charity in Britain says increasing numbers of doctors are prescribing exercise for people with depression.
The Mental Health Foundation conducted a survey of 200 family doctors in England and found that 22% suggest exercise to help people with milder forms of the condition.
A similar survey three years ago found only 5% recommended exercise to alleviate depression.
The foundation says research has shown that exercise can help people with mild forms of depression by improving self-esteem and by relieving feelings of isolation which can exacerbate their depression; exercise is also known to encourage the release of endorphins the 'feel-good brain chemicals'.
At some point in their lives one in every four women and one in every six men will suffer from depression.
The Mental Health Foundation says it is important that doctors do not just prescribe antidepressants for patients, and other options such as an increased availability of exercise on prescription is needed.
Mental health experts say exercise can help people physically, socially and biologically.
The survey found that while 61% of doctors believe that exercise therapy can be beneficial many did not have access to an exercise referral scheme.
Two thirds of the doctors wished they had such a referral scheme as there had been a marked increase in the number of people asking whether exercise could help them.
Exercise programmes organised by the Mental Health Foundation are supported by funds from the Department of Health, but are only available in some parts of the country.
Under six new schemes patients are assigned a personal trainer who devises an appropriate exercise regime for them; the results of the schemes are due to be published next year.
The Mental Health Foundation says depression is a complex illness and it is important that doctors have a range of treatments to offer people with depression.
The Foundation says there is a real need for increased availability of exercise on prescription so that it is accessible alongside antidepressant medication and psychological therapies.
The Royal College of General Practitioners says doctors recognise the benefits of exercise in treating mental illness and there is more awareness and increasing evidence that it works.
The Foundation has been campaigning for the last three years for doctors to increase their use of exercise therapy to treat mild to moderate depression.
Depression is a complicated illness, which can involve a number of contributing factors such as genes, environment, lifestyle, brain chemicals, psychology and personality; each year, almost 800,000 Australian adults will experience a depressive illness.
Depression is the third most common cause of illness among women and the tenth most common cause among men; in 2001, Australian GPs reported depression as the fourth most common illness that they dealt with.
It is the leading cause of disability in Australia and accounts for more days lost to the workplace than those lost to industrial action.
According to the World Health Organisation (WHO) by 2020, depression will be the second biggest health problem world-wide, behind heart disease.