My favourite form of excersize is walking in the countryside around my home. I like to aim for about 12 to 15 miles for a days walk, hopefully stopping at some pleasant country pubs along the route for a few beers. My preference is for a linear, rather than a circular walk, using public transport for the other leg of the journey. Occasionally I'll drive somewhere and do a circular route.
Nearly all the land in England is privately owned and there is no general "right to roam". However there are rights of way for walkers and horse riders. These are either 'statutory' which means that they are defined in law or 'permissive' which means the land owner opens them up out of the goodness of his heart. These rights of way may be either 'footpaths' - for walkers only, or bridleways where horse riders and cyclists are also allowed.
A right of way does not imply a physical path on the ground - although many are - it simply means a place where you are allowed to walk. These can take you through farms, across fields and wooded land, even through peoples gardens. Most local authorities try to provide either waymarks or signposts for these paths but I would never go out without a map (1:25000 scale) and a compass - even then I still get lost.
Although I live only a few miles from one of the world's busiest airports (London Gatwick) it's possible to walk for a whole day around here without seeing another person. Later I'll scan in some maps of these walks. Please check back later.