Feeling to nice

As I sit and pay attention to the past year of my life i realized that I am just to damn nice. I can say no but, I hate saying no. I believe that karma is real and that if I start being mean then nothing good will come out of anything. But, me saying yes 95% of the time ends up with me being unhappy and feeling used. Yes, I can say this about a few people. I have been their backbone, the one they can call for anything, the one who doesn't mind letting you use their car or sleeping on their couch. I sit around and would end up lonely and bored while they are driving around having a bunch of fun and not even attempting to try and make me smile. Well, I am tired. I have given so much of myself and I haven't received anything in return.  I have been used and abused ((not physically)) and verbally mistreated because of the fact that I am too nice. Its like people know how to use a guilty plea with me and that I will feel bad and I shouldn't. I am over making people happy and putting myself last. Its time for me to do what's best for me.