I utilize several techniques to assist my students with their anxiety and "fear" of math.
The first day, they journal about their perceptions and past experiences in math. These give me an overview of my class atmosphere. I then share how studies in nueroscience show that anxiety potentially affects their learning. I give them a sheet of positve affirmations (see attached) and ask them place the sheet at the front of their binders. If a student experiences doubt or verbally expresses "I can't do this", "I am stupid" etc, I ask them to read their yellow sheet :-)
I also use breathing and visualization techniques. Initially, I would only do this the day of assessments to assist with test anxiety. However, after very postive feedback from my students over the years, I have chosen to begin every class period. I utilize the time to focus the students, encouraging them to be present and more relaxed. I intend to collect feedback at the end of the semester through my anonoymous student evaluations.