I can second what Jeff stated. Stress is my biggest trigger. The tricky part is to learn what type of stress triggers them. For me, I can be in a very stressful situation and not have any
PVC's. Then one week later they start up. Then I have to think back to what started them up again. It is a vicious cycle but if your heart tests are normal, then you need to find some ways to relax. Hope and Help for Your nerves and Peace from Nervous Suffering by Dr. Claire Weeks really helped me. You can get the books on Amazon.
Take care
Jodie