I actually found the Be Happier [0] article to be a better source of actionable and researched-backed advice. I put a bunch of the In A Nutshell sentences into my general Anki [1] deck, and it's had a measurable effect on my overall happiness.
I know it's not recommended, but I made a single page Note Type, and just put them on there:
<b>Be Happier</b><div>
</div>Interpersonal: Give the people around you opportunities to be generous. Ask them for favors.
When it comes up, I quietly read it out loud to myself. I've found that seeing these cards often enough keeps their concepts on my mind, so when I go out with friends and someone offers to buy me a beer, I accept it and thank them, instead of refusing even to the point of awkwardness (as is my natural inclination).
[0]: http://lesswrong.com/lw/bq0/be_happier/
[1]: http://ankisrs.net/