Shlokas

माधुर्यमक्षरव्यक्तिः पदच्छेदस्तु सुस्वरः ।

धैर्यं लयसमर्थं च षडेते पाठका गुणाः ॥

[पाणिणीय शिक्षा 33]

These are the six qualities of a good speaker: fondness/sweetness (in spoken words), clear pronunciation, meaningful splitting of words, the right tone, self-confidence, and good control on pace, pause, and rhythm. 

शोको नाशयते धैर्यं शोको नाशयते श्रुतम् । शोको नाशयते सर्वं नास्ति शोकोसमो रिपुः ॥  [वाल्मीकि रामायणम्, अरण्यकाण्ड - 2.62.15] - वाल्मीकि रामायणम्  - वाल्मीकि  Grief destroys one's courage. It destroys one's learning. It destroys one's everything. There is no enemy greater than grief.