First few things to look at/evaluate. What's your social circle like? Are your friends toxic (if you have them)? Do they bring you down? Do you spend too much time on social media comparing yourself to others? What are your family members like? Do you get on with them?
What's your diet like? Are you drinking enough water? Are you exercising moderate amounts? Are you getting daily time out in the sun? What's your sleep like? Poor? Do you have hobbies that allow you to express yourself (painting? music? writing? crocheting? etc.). Do you journal? What about gratitude journalling? What about mindfulness?
Like I could go on. But these are some things you could think about. Make changes gradually and try to stay consistent. But be kind to yourself if you fall off a bit, we are all human, we are not perfect. Self-compassion is important.