Practice new skills and habits
In most cases, changing who you are means doing things differently. Often, it means learning a new skill. Once you get started, take every opportunity to practice these new skills or ways of doing things.
Incorporate changes into your daily communication. Strive to interact with others as the person you are trying to become.
For example, imagine you are trying to become more assertive. You could start by taking note of situations in which you could have stated your opinion more firmly, or didn’t stand up for your own needs. Then you may work on stating your needs in a way that is not aggressive or threatening.
Skills will become easier and more comfortable with practice. It may be scary at first, but making changes will get you closer to who you want to be.