How can I help my cat be more comfortable with being held?

We adopted my cat when she was just a kitten. We had no problems with her behavior at first, but she started to dislike being held and now she just hates being held. She will twist and meow and sometimes even hiss. We have never hit her, we give her plenty of food and water, and we play with her. She is a very friendly cat otherwise...she doesn't like to be petted much but she loves being around people and us. Whenever our family is gathered in one room she will always come sit exactly in the middle of us. She is quite playful. She doesn't have any serious health problems except she recently has become very slightly overweight, and she always finishes her food. I can't imagine why she behaves like this. I always feel terrible after I try and hold her because I feel that in some way we have violated her trust. Is there any way I can essentialy make her trust me enough again to let me hold her? Please answer because I am extremely worried!!!!!