What is negative visualization in the Stoic method?
Both Marcus Aurelius and Epictetus recommend negative visualization, which becomes a positive realization once the exercise has been performed. We should remember every day that the people, places, and things we love can be taken from us. Nothing is fixed, nothing is certain. All things are born, live for awhile, and pass away. The wife, husband, or child that you love can be taken from you in a moment. Your house can burn to the ground. You could have stroke and never be able to run and play again.
To prepare yourself for all such eventualities visualize actually losing the things you love most in your life right now. Actually see in your mind's eye the death of your spouse, your child, your house burning with all your treasures inside, your body racked with pain confined to a wheel chair or bed.
Such an exercise prepares you mentally and emotionally for the changes in fortune that are a part of everyone's life. To be prepared in this way softens the blow of losing what we most love, but even more incredibly it helps us to remember to be thankful for the blessings we have been given while they are still with us.
Visualizing the death of a loved one should remind you to be thankful everyday that this person is still enriching your life. Be happy, count your blessings, and don't forget to tell the loved one how much happiness they bring you.