How do I learn how to?

stop hesitating when speaking up for myself? As I have let rude women get away with treating me unfairly in the past and it's not right at all, and just wont do, as I'm A DETERMINED Life Soldier For Sure!!!I'm a Nice person and Just look to get on with every1 but sometimes in Life I think it's necessary to speak up for myself and stand up for myself, and complain as well just like Nelson Mandela, Malcolm X, martin Luther King Jnr Gandhi and all the other great figures!!! I'm not ata ll an argumentative person but still!!!