Try listening to your surroundings for a change, rather than just looking at them. Most of us, when walking, rely more on our eyes than we do our ears; the ‘picture’ we have in our minds of the landscape is visual. Now and then it can be rewarding to close our eyes and focus on our hearing. This is a very useful mindfulness exercise, improving our level of awareness, and immersing us in the present moment.
When out for a walk take a pause to just listen. I like to find a bench, rock, or grassy bank to sit on, or sometimes I lean against a tree. Stay there until you become accustomed to just listening. Much of the time we block out the sounds of the world around us; we have learned to shut them out if they are likely to distract us from what we are doing. Now, let them flow into your subconscious mind and you may be amazed by all that you hear. Listen attentively, like an animal does when their attention has been caught by a slight rustle from something moving nearby.