Lunch, otherwise known as the one escape we get from work a day, is a key factor in work happiness.  Unfortunately, with our busy schedules today, many people either grab a snack or skip their lunch break entirely.  While there are times when you have to work through lunch, try not to make it a regular habit.  A nice break from work can recharge you for the rest of the day, making you more productive. 

Personally, it also helps to keep me sane, which is always a plus.