Don't change who you are to make someone like you
While you might find minor aspects of yourself changing to adjust to a new relationship or new partner, this doesn't work the other way. Don't change who you are as a person in order to attract somebody.
There are many ways to make yourself happier and more attractive that don't involve changing yourself! If you feel like you need to change for someone else, think about how you present yourself to others. Ask your friends and family for their honest opinions of you. You might be pretty surprised by what they say.