http://www.quora.com/What-is-the-best-advice-your-mother-ever-gave-you-1

"If you're having a bad day, ask yourself these three questions: 
- Did you eat yet? 

Most of the time, I would realize that I haven't done one of those and after fixing it, I feel much better.  The list really reminds me to take care of little things that can keep us in a good mood.