sentence: I think it 's so effective : having a long walk in the green hills that surround my town , breathing deeply , enjoying the perfume of nature and the wonderful sights and colours of flowers and trees , it 's the best way for me to clear my mind .
modified: I think it 's so effective : having a long walk on the green hills that surround my town , breathing deeply , enjoying the perfume of nature and the wonderful sights and colours of flowers and trees , it 's the best for me to clear my mind .
transformation: K, PREP, NOUN