I listened to loving kindness meditations on the way to work, finding myself filled with love for my other commuters. Three hours later, not so much.
Loving kindness for the engineer on the A-Q product team in O---, Germany who simply complained to our team that the performance environment was down instead of investigating. (Note that the failure was not with our team's services.
(My visualization trigger for loving kindness is to think of our small grey fluffy cat Greybrother, long absent physically in my life, who took his role with joy.