In some cases it is natural as a starting point for any teaching but over time fades fear and hesitation ... It may be due to lack of teaching ability of the lecture or lack of knowledge or ability to subject or lecture
I agree with most of the remarks made by my colleagues and outlined in their answers. Hesitation, lack of confidence, the fear of making mistakes, being shy, insufficient information are all the main sources of hesitation and embarrassment. Also the inability to address and convince the audience.
An experienced speaker should have overcome some of these obstacles already. A novice may be nervous (stage fright) and perhaps under- or over-prepared adding to the anxiety. Only experience can help improve confidence during presentations; there is no other substitute for it. Being prepared to present too much can sometimes spell disaster. Thus it is often smarter to have a shorter main presentation and have other back-up material depending on what questions arise. Novice speakers especially should practice well before hand and not be over-confident.
DR . J. M. Koli , DR . Naseer H. Hamza , DR . Marwah Firas Abdullah Al-Rawe , DR . Hazim Al Dilaimy , DR . Thulfiqar Salim Hussein , DR . Srini Vasan , DR . Segun Michael Abegunde , DR . Borden Mushonga , Thanks for the answers we really have increased our knowledge