Fix all grammar flaws in the given text:
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.
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 colors of flowers and trees, it's the best way for me to clear my mind.