I have long been aware that not eating breakfast tends to make me grumpy and tired, not to mention severely distracted (since all I end up thinking about is food! when is lunch coming?). But today I realized that breakfast's effect on me isn't a binary thing: there's a whole scale. Deal is, the longer I spend eating breakfast, the more I feel that the world is a wonderful place. There is also probably a correlation between the amount of sunlight falling on me during breakfast and my level of cheeriness.
I think I'm going to eat breakfast outside more often. That may well be the secret to happiness.