I have often ignored the importance of “inspiration”. It is a vague concept. Lack of inspiration can be explained as laziness.
But is it really a placebo? Sensory deprivation is not a good thing. Humans have evolved to process sensory information. The brain transforms the world, reflects on ideas and produces outputs. We need inputs. Sensual deprivation makes us sick. Therefore, inspiration can be seen as natural defending principle for health. You must see and experience things.
Following an isolating approach to tasks, for prolonged periods of time, creates states akin to sensory deprivation. All work, no play.
It is no good, one must have exploratory and inspirational activities as well as work. One thing I do for inspiration is urban sketching. Not only it is good for the eyes to go out in the sun, but it is also opportunity to do life drawing.
It is intimidating to draw in a city full of people. One good trick is to go out very early in the morning, when there are no people. But then of course, you can't draw people. At the moment of dawn there are usually very few people and the semi-darkness hides me; So this is probably the perfect time.
In any case, inspiration should be recognized as valid concept. Even if such a concept is hard to quantify (or to prove that it exists at all), there is more danger in rejection than in acceptance. Rejection means inspiration will find its way, one way or another, but the result would be suboptimal.
Books are just one case, but they are what I know best. And form them it is easy to generalize to many inputs - visual, experience-based and physical.
This is what I call the “IROKL” list:
Imagination (I); Good things are provoking my imagination, making me dream, showing me curious things.
Relevant originality (RO); Good things bring a new point of view, bring original understanding of something relevant to me.
Knowledge (K); Good things contribute to my interests, giving me knowledge.
Liberation (L); Good things liberate form the constraints of society, from the constraints of technology, from my own mind-constraints.
And here I want to make a final note. IROKL also applies to social interaction. It is harder to “itemize” social relations point by point, but still there are distinct types of relations. Some of them could well have IROKLs, and other types may be junk.
I'm more an expert on books. But society must not scare me in that respect, because civilization can’t feed just on itself. Civilization is a gigantic hereditary brain, the accumulation of countless organic brains. So I have to tap into the brain, but also tap into the primary sources.