Meditating on 1 Cor. 2:1-5 (Paul's weakness and fear and trembling), John Calvin said this:
"The servants of the Lord are not so dull as not to see threatening dangers, nor so insensitive as not to be affected by them. No! and in fact they must be seriously apprehensive for two main reasons: 1) that, humbled in their own eyes, they might learn to lean and rest completely on God alone; and 2) that they might be trained in true self-denial. Paul, therefore, was not without a sense of anxiety, but he controlled it, so that he nonetheless continued to be undaunted in the midst of crises."