Am I doing good only to receive good? How to change this?

I want to be a good person, I do what I believe is right and try my best to speak up about what I believe is wrong, I actively try to improve myself and make the world a better place, but I haven't started doing all of this until I believed I had to in order to stop repeating what I believe is reincarnation / go to a better place, I believe motive matters, in my conscious mind I do believe I'm doing this truly because I want too, but how do I know if it's only because of what I believe I might receive if I do become a "good person", how do I change my motive? How do I simply be a good person without the thought that I might benefit from this?