I discovered this exercise on Greater Good in Action, a brilliant resource for mindfulness and wellbeing.
The exercise helps you increase feelings of gratitude for positive events in your life by visualising what your life would be like without them. Designed to be done weekly, the exercise invites you to focus on a positive event in your life, such as the birth of a child, meeting a special friend or partner or a career achievement, and then imagine how your life would be different if this event hadn’t happened . By getting a taste of how things would be different with out them, you are able to appreciate their presence in your life more deeply.
Read how to do the exercise step by step here:
Mental Subtraction of Positive Events (Greater Good in Action) https://ggia.berkeley.edu/practice/mental_subtraction_positive_events