Changing Core Beliefs

Im between therapists right now, so Im looking for advice. Since about age 14 I go through periods of normality (ish) and being very down. After a bit of soul searching, I find it to be do to a core belief that nobody could truely have love for me. Intalectually, I can process it and understand its not true, but I cant internalize.
Does anyone have any CBT tricks, affirmations, or magic ceramonies to help with this? Core beliefs can be tough to change, so lets start now. Any little bit helps.

What helped me was learning how to love myself and really put myself first. If i can love myself then love from other people will come easier because i believe you cant really give what you dont have. I practiced positive talk everytime i felt negative thoughts trying to come back and also put that into practice. Hope you find the right solution for you.