An effective speech requires a passionate and confident speaker who possesses enough strength and courage to not only face the audience but convince them through his through research, knowledge, and communication skills required to effectively deliver the topic he/she is discussing.
As per the question, 'imagining oneself as a nervous yet successful speaker' functions as a tool to 'assist in overcoming anxiety(to face the crowd)' and presenting your ideas more confidently. This positive attitude would assist in convincing the audience more constructively(through efficiently conveying the ideas) and help evoke the desired response from them.
