Dr. Jud Brewer is a researcher and professor at Brown University who specializes in neuroscience, psychiatry, and mindfulness, especially around the area of habit formation and letting go of unhelpful habits. He has a well-regarded book on anxiety, Unwinding Anxiety, and has developed apps and teaching programs to help people deal with anxiety and other difficult habits. This article from his blog looks at the nature of “what if” thoughts and describes approaches for loosening the habitual patterns of anxious thinking associated with anxiety. You can find his article here: What If Thoughts: Why Your Brain Gets Stuck in Worst-Case Scenarios
Judy Lief presents a good article on the nature of anxiety from a Buddhist perspective and discusses ways in which we can use mindfulness to help unravel anxiety, which is based on our uncertainty about the future. She discusses the ways in which mindfulness, which focuses on the present moment, can help us to let go of anxiety. You can find her article here: How Mindfulness Can Help Ease Anxiety