David K. Reynolds has introduced several variations of daily Naikan [self-reflection] that may be practiced progressively and reveal different aspects of our daily interactions with life: Do Daily Naikan on:
1. people whose faces you know but whose names you do not know (e.g. the bus driver who took you to the subway stop this morning.)
2. people whose faces and names you do not know (e.g. the person operating the subway train)
3. living nonhumans, such as the cow that provided the milk for the coffee
4. objects such as a car or cassette player (a friend of mine, a professional piano player, did daily Naikan on his piano)
5. forms of energy, such as electricity and heat.
— Gregg Krech, Naikan