[/quote] You’d get bored easily. You need about minimum 20 acres realistically.[/quote]
I believe that running, especially running outside on a trail, has so many variables that it is difficult to become easily bored with it.
The weather is always changing, The external stimuli such as temperature, wind, humidity, lighting, sounds, trail tread etc. will be constantly changing and different every time you are out there. Unless the land/habitat is sterile and barren, there will be different insects, birds, trailside vegetation, that is changing.
Trails are very different when you turn around and run them in the opposite direction.
You have the ability to infinitely vary the intensity, duration, and frequency of your runs. You do not have to run on your personal backyard trail every day. You can vary stride frequency, length, footplant, shoes, etc.
Since its your land and your trail you can change vary the configuration, length, tread surfaces, etc. You can also modify the land/habitat by planting or removing different vegetation.
How you perceive and react to all the variables also changes.