In the New York Times recently "The Difference Between Worry, Stress and Anxiety" by Emma Pattee explains:

• Worry is mental — it focuses thoughts on an issue
  • Put a time-limit, like 20 minutes, on worrying about a particular problem
  • Push yourself to decide on an action to take
  • Write down worries to focus and calm your mind
• Stress is physical — it prepares the body to respond to a threat
  • Get exercise to help recover
  • Attend to what you can control and accept what you can't
  • Don't compare your stress with other people's — everyone is different
• Anxiety is both mental and physical — it's worry + stress without a threat
  • Limit sugar, alcohol, and caffeine
  • Refocus your senses — wiggle your toes, listen to music, take a little exercise, look around, touch something soft, ...

Pattee's bottom-line: get enough sleep, eat regular nutritious meals, and move your body.

And a useful proverb, independent of the article:

_{(cf Optimist Creed (1999-04-16), Purpose of Meditation (2009-04-07), Don't Panic (2010-11-17), Mind Like Water (2011-12-24), It's Not So Bad (2012-03-13), Mantra - Be on Good Form (2016-05-10), ...) - ^z - 2020-03-04}