How can I get to the fields outside Stansted?

This might be a silly question and I'm not sure if it will make sense, but anyway; Every time I go to London and Iand at Stansted Airport, I take the Stansted Express to Victoria station and I really do think that this train journey is the most scenic one of the London airports. Now I just came to think of my first time on the train. I wasn't very fascinated by England and didn't really want to go there, but once I saw the landscape I was overwhelmed by fascination. I remember seeing a lot of farmland, extremely green fields with horses and beautiful trees and nice English houses. It was very tempting to be able to be at one of the fields at a warm summer day and just run around and feel free, haha, as crazy as that might sound. Now I came to think "Why not try to do that?". However, I can imagine that all of this is private property! Any ideas? :-D