I think this segment of Emerson's Self-Reliance focuses on the theme of confidence. If we cannot believe in ourselves, we have already defeated the purposes and aims we set out to achieve. In reference to the entire paragraph, Emerson asks us to consider doing three things:
1. Notice where you are and accept your circumstances. Then, choose to work with them:
"Accept the place the divine providence has found for you, the society of your contemporaries, the connection of events. Great men have always done so."
2. Consider the confidence of children and employ that with the knowledge of being an adult:
"Great men have always do so and confided themselves childlike to the genius of their age, betraying their perception that the absolutely trustworthy was seated at their heart, working through their hands, predominating in all their being. And we are now men, and must accept in the highest mind the same transcendent destiny; and not minors and invalids in a protected corner."
3. Being grown adults, consider employing the powers of teaching, giving, helping and fighting evil.
"And we are now men, and must accept in the highest mind the same transcendent destiny... but guides, redeemers, and benefactors, obeying the Almighty effort, and advancing on Chaos and the Dark."
I think given these above principles, Emerson is charging his readers to live to the best of their abilities which means acting on the good we have inside of us. Sometimes we think of a right thing to do, but do not have the confidence to follow through with it. If it is right, it must be done.