Just a small thing that I do:
I'm still in high school, so many of my friends have a tumblr. I don't, so I'll drop by once in a while and leave an anonymous question, reminding them that they are loved and to keep a smile on their face. And I have to admit, it makes me smile, too, when I swing by again and read what their answer says.
Here's an example:
Anonymous: Hi there. May I just take a moment of your time to tell you that you are amazing, and to remind you to smile. C:
Awh. Thanks bud. (: This actually did make me smile and it means more to me than you would think. :D