This is advice from Darin Strauss, author of Half a Life.
When writing a draft of your memoir, try using third person instead of first. Strauss says what makes writing about ourselves hard is doing so impartially. It’s easy to award a full pardon to our “I” sins, or at least unfair points. Looking at yourself as you would a character helps remove that extra pinch of sugar. When you think you’ve gotten it right, fair and unsentimental, change the draft back to first person.