Consider at least one of Thoreau's suggestions for living found in your reading of Walden. Examine the suggestion, pointing out some problems with applying it to real life.
What is Thoreau's purpose in proposing this example?
In Walden, Thoreau recounts his time living, for the most part, alone. His goal with this project was to live deliberately, to eliminate inessential tasks and luxuries, and to be as efficient and simplistic as possible. In the long first chapter, "Economy," he writes:
To be a philosopher is not merely to have subtle thoughts, nor even to found a school, but so to love wisdom as to live according to its dictates, a life of simplicity, independence, magnanimity, and trust. It is to solve some of the problems of life, not only theoretically, but practically.
This goes to the heart of your question. His purpose was to practically apply his philosophical values. In paying attention to the necessities of life, Thoreau thought this would free men of their anxieties about superfluous thoughts, making them more keen observers and also, given that they were not wasting time on unessential pursuits, they would have more time to think and read. Hence, the chapter on reading where he says, "Why should we leave it to Harper & Brothers and Redding & Co. to select our reading?" This is a prescient thought considering how we are now bombarded with media about what to watch and read. I imagine Thoreau would have similar criticisms about a majority of television shows and certainly gossip magazines. One of the problems with applying his philosophy in real life (more problematic now than in Thoreau's time) is learning to think for yourself, ignoring the constant influx of media noise and mind-numbing entertainment.
Thoreau also says, in the chapter on "Solitude," "I never found the companion that was so companionable as solitude." Although he directly favors solitude over society in this quote, Thoreau considers the times when people meet (at meals, the post office) are usually composed of ritual sayings or small talk: nothing really profound or meaningful. Back to your question, how do you apply the fruits of solitude in real, social life? Well, again this is more difficult now because of the fast pace of life. But Thoreau would implore us to make our social interactions more meaningful and this might require us to be alone more if only to come back to others with something more meaningful and profound to talk about.
Thoreau's praise of self-reliance and individualism play into this call for solitary thinking and living. Probably the most obvious obstacle is how to live as an individual in society. In "The Village" chapter, he relates how he was put in jail for not paying taxes in protest of slavery. No doubt, this is an example where applying philosophical values practically can be problematic or, let's say, inconvenient. Consider the "Occupy Wall Street" movement. Some of these people have been arrested, some have lost their jobs, etc. But in their and Thoreau's cases, these acts of "civil disobedience" were means to an end of liberation. In terms of "problems" of applying some of these suggestions to real life, these might be considered worthwhile problems because of the goals they intend to achieve.