Yes it is but you will have to stand up for yourself. This isn't to say you have to stop being your generous, forgiving, nice and trusting self but you need to be much more selective in who you give it to. If someone has abused this in the past, then they probably don't deserve it in the future unless they can show that they will not abuse it anymore (this usually takes time to rebuild trust).
By letting them feel that awesome feeling of getting thrown under a bus!
Bite their ankles!
Grow a spine and an attitude. Tell people to **** off and they will look at differently...
Bitchier yes, angry no. Having an attitude and a backbone is not being angry. It is being rather confident about who you are and expressing that confidence... or should I say being a clever ***** not an angry *****...
Beat them within an inch of their life.
Why in the world would you allow someone to walk all over you?? You have to have respect for yourself before anyone else will respect you!