I don't think I could be a political activist.
Oh that's nice, I have always known that efforts to promote, impede, or direct social, political, economic, or environmental reform. I want to change things I don't like in the society 
I can understand that, but my opinions change too often for it to be practical
Activism can be as simple as writing letters to newspapers or to politicians amongst others
That is true. I guess I thought of it as more extreme. There are certainly things I could do.
Well if you think that's extreme then what about preferentially patronizing businesses, rallies, street marches, strikes, sit-ins, and hunger strikes?
That is more what I was thinking of.
Also  different forms of art (artivism) can be used to express activism as well