Happiness at work - how to boost your energy on the job

I came across a study recently that found that even just a half hour of exercise - any form of exercise - during the workday (for example, taking a walk or a yoga class during your lunch break), significantly increases productivity, concentration, ability to make decisions, and a feeling of happiness while you're on-the-job.  Pick a place for lunch that's a few blocks away from your office, and walk there briskly - it will make a real difference (especially if you eat something healthy for lunch, and skip alcohol and sugary drinks).