I will approach grief and thanksgiving from opposite ends of the emotional spectrum. If you still have anger or are holding a grudge against someone who passed away, I encourage you to try this thanksgiving exercise. If you want to celebrate the life of a loved one, thanksgiving may be an opportunity to rejoice in what the person meant to you. If you are holding anger against the person who died, it may be helpful to you to try and find some way to recognize any positive influences, gifts, or memories the person left behind. Building a positive list of memories may help diminish ongoing hate and anger. At first, your emotions, hatred, and anger may hold you back from finding positive things to say about someone you dislike. The exercise of finding positive memories may help diminish the block that hatred has created. Remember that the person may have truly hurt you, wronged you, and left you predominately scarred, but after they are dead, you hold all the cards to free your emotional memories and negative feelings. If you had a positive relationship with the person, this exercise would be rewarding and refreshing as you remember the beautiful things the person did for you or said.
Don't press this thanksgiving exercise if you are still holding anger against the person. I encourage you to try and find one small thing to be thankful for this person. One small item may be the first step toward healing. If you do not hold any anger against this person, use this exercise to privately celebrate the life of the person you lost through death. Thanksgiving is a spiritual exercise where you find the gifts that God placed in the person's life for you to see.