Thanks for your replies everyone! I'll see if I can overcome this.
I only approached someone once before. It was to give someone at Walmart an Iams leaflet (she had Iams products in her cart) and I was nervous as hell. Especially because instead of reading it she asked me what was wrong with Iams and she had children with her, so I had to try to explain it generally and avoiding any gruesome detail, and just told her that she could read the leaflet to find out the rest. When I was done talking to her, she thanked me. After I walked away my hands were literally shaking.