Sitting by the tree, just close your eyes, feel the tree. Hug the tree, just be one with it, as if you are with your beloved. And sometimes... and it is not predictable; I cannot say that it will happen each time. Only once in a while it will happen -- because it has to happen in spite of you, that's why only once in a while.
Or, loving your woman, melt into her warmth. For a moment forget sexuality, for a moment forget all that goes on in your head, in your fantasy. For a moment just melt into the real woman. Don't carry any pornography in your head, don't make sexuality something cerebral. Let your sexuality be a deep sensuousness, sensitivity, a gut feeling.
Melt into the woman, as if you are again a child in the mother's womb. Unless you have known this with your beloved, you have not known your beloved. A child again in the mother's womb, absolutely together, all distances gone -- and in that moment you will know what surrender is.