The religious motif
When Roosevelt opens the speech by saying, "I wish to preach," he invokes religious ideas, like a preacher giving a sermon at a church. The effect is that he communicates with ultimate authority, because he appeals to the religious sentiments of the people, basically arguing that those who disagree with him will be wrong for doing so. This use of religion continues, and as the speech unfolds, it becomes an argument about how the people should obey their ethical compass by working hard.
The symbolic meaning of work
For Roosevelt, the value of work was not in the actual accomplishment of a task, but rather in the voluntary sacrifice of will. By agreeing to work hard, by deciding to set high goals and high expectations, the civilians could save themselves from their poverty. Roosevelt also advocates for the sciences and the arts, reminding people that although blue collar, manual labor is honorable, those who don't like to do it can still get jobs in the arts and sciences.
The motif of fear or aversion
Throughout the document, Roosevelt's speech argues that the only reason someone might not want to do the right things in life is for fear's sake. He implies this early on by saying, "the highest form of success comes not to the man who desires mere easy peace, but to the man who does not shrink from danger." This implies that the people who prefer safety and comfort are cowardly. This is certainly raising the bar of bravery.
The symbolic leader
Roosevelt clearly offers his authority on many issues outside the purposes of his political office, so to speak. For instance, offering citizens personal advice about how to succeed in life seems to be unusual for men in leadership who usually deal with matters on a more matter-of-fact level. But that is because Roosevelt is accepting that he himself is a kind of symbol, and he uses that chance to offer people some encouragement for approaching life more strategically.
