I feel like I'm currently walking the fine line between the two ('living' and 'existing'), though I do not have any severe sensory issues to deal with...
Currently, I enjoy going to the park every morning and be among the water fowl... ducks, rails, swans; to me, it's an energizing experience that pulls my attention away from the hectic human world and opens my eyes to a different, more pleasant manifestation of 'life'.
I am starting to enjoy my hobbies again after an extended period of depression and apathy, so I am happy about that. I can also identify with the things PlatedDrake said: I'm very much aware of the constant change that's inherent to life, but that was something I took a long time learning. I'm very glad to say that I finally "live in the now" these days. But I also have that fear of failure Drake mentioned, and I have indeed been dissuaded from pursuing goals in the past because I figured others would be far, far better than I, and perhaps I would be unable to defeat.
But to sum it up, currently I feel very much alive, even if my life isn't that interesting or spectacular.
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clarity of thought before rashness of action