“A smile from someone you like”
/u/portajohnjackoff, https://www.reddit.com/r/AskReddit/comments/5dlv49/what_are_the_little_things_that_make_a_day/da5igb0/

A compliment from someone who you highly respect.
/u/imfreezingmyassoff, https://www.reddit.com/r/AskReddit/comments/5dlv49/what_are_the_little_things_that_make_a_day/da5lkdl/

Small acts of kindness to strangers may seem trivial but they can make a world of difference in improving another person's day.
/u/veloquacat, https://www.reddit.com/r/LifeProTips/comments/5epg34/lpt_small_acts_of_kindness_to_strangers_may_seem/