Everyone goes through different experiences. These experiences cause you to respond to them in different ways. Such experiences over time shape our identities.
Your current behaviors are simply a reflection of your current identity. What you do now is a mirror image of the type of person you believe that you are (either consciously or subconsciously).James Clear, Author of Atomic Habits
To change yourself for the better, take stock of the events happening in your day-to-day life, analyse how you respond to them and make the change there. You will be surprised to find how small nudges can change the direction of your life!