If they feel they have a "mission" to complete your children will be much more willing to walk.~
Tourist offices will be your best allies here as many of them have maps with orientation circuits that are accessible throughout the year. Using these resources, your children will have to find the locations shown on the card ensuring they make their way along the route.~
If you do not have an orientation circuit at your hiking location, you can use the markings that appear along the footpaths. This type of activity teaches children to find their way around. So they become your hiking guide!~
For the littler ones, you can prepare a simple list of things to find during the hike so it becomes a kind of treasure hunt: sticks of a certain shape, stones of varying shades, pine cones, bark, flowers, leaves of certain species etc. Let your creativity run free and let them add to the list for next time! You can also build a herbarium with the older ones.