Your inner mettle may not be easily altered, but with the right tool kit, some aspects of personality may be works in progress.
Become a believer. Trust that you can change and you are far more likely to do so.
Find your signature strengths—and that means discover them. Don't assume that you know your strengths in advance. See authentichappiness.sas.upenn.edu for a questionnaire that measures character strengths.
Identify—and reject—overly pessimistic beliefs. Rigidity might be the result of a belief as well as inner temperament.
Tap someone to help you meet a goal.
A systematic approach with a good friend or
therapist can help you buckle down.
Take risks. Confidence increases with persistent experiment. Sign up for a stand-up comedy class. Because people do change with time, you may find that attending parties alone—an act that petrified you two years ago—is now a manageable challenge.
Find the right fit. Keep in mind that traits are not necessarily constant across all situations. Some people are anxious interpersonally in intimate settings, for instance, but they nonetheless enjoy the lime (or vice versa). Find the niche where your traits are most useful and where you feel best.