Travelling on a long journey can be extremely boring and can also make you sleepy, which is far from ideal if you are the driver. Firstly you need to plan out scheduled stops, not only for toilet breaks but to give all occupants time to stretch their legs and just have a bit of a change of scenery. This is also a good time to get a tea or coffee and perhaps something to eat.
If you are travelling with children then you will need to make sure you have activities planned that they can do in the car. Depending on their age there are lots of things you can do, but often children get bored quite quickly so it is worth having a number of activities planned.
Some people have a DVD player in car allowing the occupants to watch a movie for the trip, others chose to play travel games or do reading or drawing. Make sure that you have everything you need to hand to save you having to keep pulling over to get things out of the boot of the car.