The basic cause of shyness is hard to pin-point. Everybody is shy to a degree, often therapists refer to a Personal Shyness Barrier - this is the boundary we all have that limits our ability to assert ourselves.
These limits range from simple situational shyness (eg meeting someone new, asking someone out, ringing a date) to more comprehensive and serious conditions where shyness is always present and the person is ‘socially disabled’.
Shyness always has a core root - low self esteem, self perceptions of ugliness, parental influences, fear of rejection, etc. The good news is that shyness can be helped, but left untreated can grow to being a very big problem.
Many people later in life experience feelings of social isolation and loneliness as a result of controlling shyness. This intern can lead to feelings of depression, stress and/or anxiety which may result in heavy drinking, drug use or a total dissatisfaction with life and suicidal tendencies.
To overcome shyness first one must identify when shyness is present and what is the trigger for these feelings. When appropriate write these experiences down then identify the myths and facts about the fears associated with the trigger.
If feelings of shyness become a controlling force in a persons life, limiting our ability to meet people, make new friends and experience the fullness of life, then it is advisable to seek professional help.