It is definitely difficult to become self-reliant in the way that Emerson is describing in this essay.
To know why, we need to think about how Emerson defines self-reliance. Basically what he is saying is that you need to be yourself. You need to rely on what your own conscience tells you rather than doing what society thinks you should do.
Think about the difficulties this would cause. As a teenager, you are surely aware of how much trouble a person can get in by being different. Teenagers often treat people very badly when they act in ways that society (other teenagers) does not like.
Among adults, it is not really much better. At the very least we have to do what society says if we are going to keep our jobs (most jobs at least). Typically, a person needs to act in certain ways to maintain relationships with other people.
So, unless your conscience conveniently tells you to act in socially acceptable ways, following Emerson's recommendations would be very difficult.