Another way you are responsible for loving yourself is not letting others take advantage of you. Sacrificing to put your neighbor’s needs before yourself is a good thing if it is done with their good and your good in mind.
But, to sacrifice ourselves for others, does not mean to suffer silently and willingly when some person or organization demands more from us, consistently, than is offered in return.
We are not called to support tyranny, or allow ourselves to be treated like slaves. It is not virtuous to be victimized by a bully, even if that bully is yourself.
I am a sinner but I need to love and forgive myself just like I am called to forgive others.
To start with loving yourself means defending yourself against others taking inappropriate advantage over you. You must learn to bargain for yourself so that you don’t end up being stepped on. In the long run this will only make you resentful, vengeful and cruel.
You need to determine how to act toward yourself so that you are most likely to become, and to stay, a good person. It is good for you to be good to yourself to make the world a better place. It is good for you to treat yourself like God wants to treat you. As his precious son or daughter.