If you mean traveling by car you just have to chart the stopover because children get bored in long trips. It would be a good idea to bring along snack foods and drinks that would give them some excitement.
Would you believe that we bring along our 3 dogs when we go on vacation as far as 8 hours drive. We just stop every 3 hours or so and our dogs are fine because they used to traveling.
Depends on age and if they hate going on travels. If you're on an airplane and going on holiday then make sure you at least bring a tablet to keep them occupied on the plane. If it's a car travel then make sure you bring a few devices and maybe some games like Scrabble or a pack of cards. And don't forget plenty of snacks cause we know how children are when you give them a sweet or something sugary.