There are plenty of unselfish reasons to write about memories, but there’s nothing wrong with doing it simply for yourself. You can write about memories to preserve your stories while memory serves, for the joy of writing, or to work-through your past. You can also write about memories because telling your stories is therapeutic.
You can Keep your Writing Private
You don’t have to share anything you don’t want to share. Once you’ve written something, you can rip it up, delete it, or burn it. No one has to know. After my parents’ deaths, I wrote them a highly personal letter and placed it under Forget-Me-Not’s that I planted at their accident site. The process of writing the letter and “giving” it to them helped me process my grief, but no one (even me) will ever see my words.
When you write about memories, sharing is completely optional. They are your words and thoughts. You get to decide their destiny.
When you write about memories, you can improve your health. The rewards of writing therapy are not simply intrinsic; studies show that patients experience increased well-being and relief from a wide variety of symptoms. 
Writing Helps Us Feel Productive
Writing provides a concrete measure of what you’ve done. You’ve written a page, conquered a subject prompt, or reached out to a loved one. When you write about memories or tell your stories on paper, you have observable proof of your progress.
Writing about Memories and Stories Provides Connections
Writing can be a defense against social isolation. When you write about memories, you are forging connections with loved ones with whom you shared your past. If you choose to share them, your writing can bring you contact and connections to others. You can even reach out to total strangers through your writing. You don’t have to wait until you’ve shared your writing to feel the connection. At least for me, writing about memories with the intention of sharing provides me with a connection to my family—even future family members.
Writing Stories Help Process Major Events
Sometimes all the emotions floating around in our brains prevent us from achieving any clarity about our situation. Stroke victim Carol Keegan, writes, “I had found the simple process of finding words to convey my fears and resentments softened my fierce need to make sense of the experience… The more I wrote, the more I discovered inner resources that my pre-stroke self had never been forced to call on.” Write about memories to process past events or circumstances. You gain perspective that internal rumination would not grant you.
Writing about Memories to Process and Express Grief
In times of intense grief, we have trouble grasping why the earth continues to turn on its axis when ours has come to a screeching halt. Sharing our memories brings a consoling sense of shared loss and connection. Perhaps this is why writing in the face of loss is also a recommended grief therapy.  Experts Elizabeth Kubler-Ross and David Kessler express it eloquently: “Grief must be witnessed to be healed. Grief shared is grief abated.”
Writing Allows Us to Exercise Our Creative Side
Writing provides an outlet for creative expression. Don’t be afraid to experiment; try your hand at different styles of writing. Write about your memories and have fun with it.
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 “Making the Most of Memories: Creating Memory Books and Activity Kits,” Alzheimer’s Arkansas Programs and Services. Accessed April 18, 2012, http://alzark.org/caregiver_information/memory_book.pdf.
 Carol Keegan, “Therapeutic Writing: Life Stories Punctuated By Healing,” StokeAssociation.org, modified March 21, 2013, http://www.strokeassociation.org/STROKEORG/StrokeConnectionMagazine/SubmittingYourStory/Therapeutic-Writing-Life-Stories-Punctuated-By-Healing_UCM_450077_Article.jsp.
 Bodil Furnes and Elin Dysvik, “A Systematic Writing Program as a Tool in the Grief Process: Part 1,” Dove Medical Press, Ltd, December 6, 2012, Abstract accessed April 18, 2012, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3003609/.
 Nance Cunningham, “Taking care of grieving through poetry: memories of palliative care’s presence or absence.” Families, Systems & Health 27.1 (2009): 98+, Academic OneFile, accessed October 27, 2012, http://dbproxy.fh.farmlib.org:2305/ps/i.do?id=GALE%7CA196533284&v=2.1&u=lom_metronetmnfc&it=r&p=AONE&sw=w.
 Elizabeth Kubler-Ross and David Kessler, On Grief and Grieving: Finding the Meaning of Grief Through the Five Stages of Loss, New York: Scribner, 2005, 63, accessed online September 7, 2012, http://books.google.com/books?id=KLXjB6Car9UC&printsec=frontcover#v=onepage&q&f=false.