I also struggle with boundaries a lot! I read a few books last year that were helpful: 'When I say no, I feel guilty' and 'Boundaries: When to Say Yes, When to Say No.' The second book is written from a religious perspective. I am not religious, but I got a lot out of the book anyway.

The biggest improvement I've made in the past year or two is letting go of the desire to analyze my 'no' to death. I used to worry a lot about whether it was 'right' to say no. Now I still worry probably more than I should, but a lot less than I used to

Is there some area in particular where you feel like your boundaries aren't good?