Think of Mahatma Gandhi for example. Most people did not find him to be attractive or impressive as far as his physical make - up was concerned. Short, meek looking, bard, dhoti - clad old looking man moved the whole India behind him. Even today he is known his 'Personality' which had its impact, and force with an everlasting impression on the people around him that made him the man of world - fame. Personality is the sum total of all physical, mental and emotional attitudes, values, interests and motivational factors.
Personality is the core potential that determines one's success in life and career.
If you feel depressed or disheartened because you think that you are born with weak personality - stop thinking negatively. It is the environment that can be manipulated to get the desirable positive effects in shaping the personality. This is obviously an extreme view that some behaviorists have taken to focus on the role of environment in personality development. The fact remains that enriching the environment of the individual does show significant improvement in developing your personality. You must use your brain and understanding before you join such courses.