Rambling and walking are popular pastimes which can keep you fit and active - this doesn't necessarily have to be too strenuous. Walking is free, easy and can improve your general health and wellbeing. Some local societies for the blind have rambling clubs.
The Ramblers Association will be happy to put you in touch with a rambling group in your area. You can go on pre-arranged walks in the countryside or in towns and cities if you prefer.
The Sensory Trust can also give details of countryside sites which are accessible to blind and partially sighted people.