These days very few people keep diaries or journals. The result is history lost. Every human being is responsible for 200 years of history. This may seem an outrageous claim, but take a moment to think. My grandmother was born in 1880. She passed away in 1969. From her I heard stories about her parents, particularly the great grandfather who fought in the Civil War. My youngest grandchild is likely to live well past 2080. From me he will hear all the family history and pass them along to his children. Stories not shared are stories lost. Even the most dedicated genealogist can only fill in facts and figures. They cannot recreate a lost piece of family history.
It is easy to say, "My children aren't interested". Write it all down anyway. About the time they get very interested, you will be gone and they will be kicking themselves that they never asked the questions that now are driving them up a wall. "I don't have children, why should I keep a journal". There are libraries all over the planet with shelves devoted to genealogy and there are people reading them for a flavor of how real people lived. Missing diaries are missing lives.
Writing is too difficult. In an age of blogging, this objection almost seems silly, but I'll make it easy for you. Simply gather and label every picture you own. At some point in the future, no one will have to ask, "Who is that person with mom?". Next gather every document you own relating to births, deaths, and marriages and put them in one safe place. This means that no one in the future will have to pay to recreate these documents. Finally write a simple list of years from the day you were born until the present. Then write a note for every year either that you remember or that was told to you. The notes do not have to make sense to anyone else, they are for your use to jog your memory of events.
Go to your nearest stationary store and browse. Virtually every one has something along the lines of "grandmother remembers". Buy it, take it home, gather your notes, and fill in the blanks. You do not need to do a formal genealogy if that isn't your interest. That can be left for someone else, but they will need the stories and clues you leave behind.