No work or love will flourish out of guilt, fear, or hollowness of heart, just as no valid plans for the future can be made by those who have no capacity for living now.
Books are totally useless unless you take their advice. If you just keep reading them, thinking "that's so insightful! that changes everything," but never actually doing anything different, then pretty quickly the feeling will wear off and you'll start searching for another book to fill the void.
You are the sum total of everything you've ever seen, heard, eaten, smelled, been told, forgot - it's all there. Everything influences each of us, and because of that I try to make sure that my experiences are positive.
Whoever fights monsters should see to it that in the process he does not become a monster. And if you gaze long enough into an abyss, the abyss will gaze back into you.