If you want to experience the being within a tree. Take a large tree that feels special to you in some way. Stand within the space of the tree and take a few moments to watch you breath going in and out. Feel your feet on the ground.
Feel into the canopy. You can do this with your eyes open or closed. Let your subtle awareness merge with the canopy of the tree. Feel the main branches, let your peripheral awareness spread out to include all the leaves. Take a few moments to feel the canopy in your energy while asking your self tactile questions such as, dose it feel heavy or light, moist or dry, brittle or supple or example. Be aware of any subtle impressions you notice.
Then extend your energy below the ground. See if you can feel the root bowl of the tree. Feel if the roots are moist or dry, if the roots feel healthy or sock, flowing or stuck for example. Take your time. Be aware of any subtle impressions.
Be aware of the whole tree in your energy. Above and below the ground. Feel its movements. If there is a breeze, let yourself feel the breeze through its leaves. Feel if it feels wet or dry, if the tree is happy, or sad, carrying an unnecessary burden or youthful and straight.
After a while you might be lucky enough that the being of the tree will pop out and show itself.
Once you have repeated this process with several trees, you will notice that you do know, that for example, one tree feels happier or more burdened, one tree feels angry and brooding, and another feels welcoming for example. Some trees are incredibly wise. The more you practice the more aware you become of the nature of these subtle beings.
Next time you are lost in thought and walking past, you might find the tree will reach out and say hello to you.