A walk. Simply just a walk, yet I would interlace with scenes moving in and out not necessarily sequentially of that person's life who is on the walk. I feel and think when we reminisce we don't do that sequentially and draw parallels and connections without congruency.
The primary walk may take place in really any setting - city, park, countryside, etc. as any stimuli will have a cause of memory occurring. I think it would be cool to just discover the individual famous or not as that walk occurs. Certainly those interconnected memories would form a story with available plot, sub-plots, character development, morals, and more.
Maybe, but not necessarily, walking with a friend, be that a relative, of intimacy in sharing. Possibly a pet dog? Where in life most likely of least the age of thirty, yet possibly much later may be more intriguing.