Breakfast, because it starts off the day and it's so versatile:
always orange juice to start (for vitamin C), then a choice of -
traditional cooked breakfast (usually a Sunday brunch for us, or an English treat for our French friends!),
French croissants & jam with coffee,
good old porridge sweetened with lots of honey,
or just lovely crunchy toast with marmalade.
A good mug of filtered black coffee is a must to finish.
Puts me a good mood to face the rest of the day!