Answer by taking a quote from the following article:

Henry David Thoreau (see name pronunciation; July 12, 1817 - May 6, 1862) was an American essayist, poet, philosopher, abolitionist, naturalist, tax resister, development critic, surveyor, and historian. A leading transcendentalist, Thoreau is best known for his book Walden, a reflection upon simple living in natural surroundings, and his essay "Civil Disobedience" (originally published as "Resistance to Civil Government"), an argument for disobedience to an unjust state. Thoreau's books, articles, essays, journals, and poetry amount to more than 20 volumes. Among his lasting contributions are his writings on natural history and philosophy, in which he anticipated the methods and findings of ecology and environmental history, two sources of modern-day environmentalism.

Most of the luxuries and many of the so-called comforts of life are not only not indispensable, but positive hindrances to the elevation of mankind.  Thoreau was an early advocate of recreational hiking and canoeing, of conserving natural resources on private land, and of preserving wilderness as public land. He was himself a highly skilled canoeist; Nathaniel Hawthorne, after a ride with him, noted that "Mr. Thoreau managed the boat so perfectly, either with two paddles or with one, that it seemed instinct with his own will, and to require no physical effort to guide it."  He was not a strict vegetarian, though he said he preferred that diet and advocated it as a means of self-improvement. He wrote in Walden, "The practical objection to animal food in my case was its uncleanness; and besides, when I had caught and cleaned and cooked and eaten my fish, they seemed not to have fed me essentially. It was insignificant and unnecessary, and cost more than it came to. A little bread or a few potatoes would have done as well, with less trouble and filth."  Thoreau neither rejected civilization nor fully embraced wilderness. Instead he sought a middle ground, the pastoral realm that integrates nature and culture. His philosophy required that he be a didactic arbitrator between the wilderness he based so much on and the spreading mass of humanity in North America. He decried the latter endlessly but felt that a teacher needs to be close to those who needed to hear what he wanted to tell them. The wildness he enjoyed was the nearby swamp or forest, and he preferred "partially cultivated country." His idea of being "far in the recesses of the wilderness" of Maine was to "travel the logger's path and the Indian trail", but he also hiked on pristine land. In the essay "Henry David Thoreau, Philosopher" Roderick Nash wrote, "Thoreau left Concord in 1846 for the first of three trips to northern Maine. His expectations were high because he hoped to find genuine, primeval America. But contact with real wilderness in Maine affected him far differently than had the idea of wilderness in Concord. Instead of coming out of the woods with a deepened appreciation of the wilds, Thoreau felt a greater respect for civilization and realized the necessity of balance." Of alcohol, Thoreau wrote, "I would fain keep sober always.... I believe that water is the only drink for a wise man; wine is not so noble a liquor.... Of all ebriosity, who does not prefer to be intoxicated by the air he breathes?"

What did he believe about instead if neither rejected or embrace wilderness?
he sought a middle ground, the pastoral realm that integrates nature and culture.