Thing don't always work as we would want them to. Machines break down. People don't remember to do what they said they would. Stores run out of things, and sometimes they are closed when they were scheduled to be open. Letters we were supposed to receive aren't always delivered on time. Messages are not always given to us. The amount of things that don't work out the way they usually do is enormous.
How will your emotional reaction be towards these types of occurrences? It's up to you.
Some people choose to be frustrated and disappointed. They feel stress and distress. They lack a feeling of well-being.
A master of gratitude will use all occurrences to gain greater mastery over gratitude. Each time something doesn't work out the way they would want it to, they remember to feel grateful for all the times that things do work out well. This pattern of thinking gives them feelings of happiness and joy.
When a machine breaks down, they are happy for all the times when this and other machines do work. If someone doesn't remember to do what he said he would, they are grateful for all the times this person did remember. And they are grateful for other people remembering to do what they said they would. When stores run out of things, it's a reminder to be grateful for all the times this store and other stores had the things that you needed and wanted. A message not given is a reminder to be more careful to give over messages yourself, and to be grateful for all the messages that you did receive. A letter not received on time is a reminder to be grateful for all the letters you did receive on time. All the many things that don't work out the way they usually do, are reminders to be grateful for all multitude of things that do work out.
A person who integrates this pattern will live a life of gratitude and happiness.
(From Rabbi Zelig Pliskin's book: THANK YOU! Gratitude: Formulas, Stories, and Insights: Artscroll Publishers)