I hardly say no, what should I do?

I admit, nahihirapan akong tumanggi sa mga tao. I grow up thinking na if I can right now, then I do it. If it seems harmless, I do it.

I grow up sacrificing what I want to do for the sake of helping others. I always think about making difference at someone lives not knowing they are just taking advantage of me.

I am too blind to see if the person is just using me or really need my help.

In the end, I'm the one hurting, I'm the one overthinking, I'm the one exhausted.

It is really hard for me to know when to say no. Any advice bros?