Daily Power! Action Point! Utility Power! Extended Rest.
Is this what battles sound like in your campaign? Do your players use up all their resources in their first encounter of the day, then take an extended rest?
The problem with over-resting is that it renders encounters easier. If a Daily Power is used during every encounter, then it's not really a Daily Power, is it? Players will not ration their combat resources, but simply unleash their entire arsenal right after initiative is rolled.
Here are three ways to deal with the problem of over-resting.
Beat the Clock
An extended rest takes six hours, versus the five minutes of a short rest. If you design adventures that have time-sensitive components, then your players won't have the luxury of taking extended rests after each battle. Maybe the assassin's trail gets colder with each passing hour. Maybe the cultists will complete their ritual by midnight. Maybe every day means another villager killed.
Here Be Dragons
A party is much less likely to rest if it cannot find a safe place in which to do so. Don't give them one. Make them hear footsteps and growling around their forest camp. Make the only available room at the inn have a broken lock and a window on the ground floor facing the slums. Make the only defensible room that the party has cleared in the dungeon have a ceiling that may collapse at any moment.
Bring the Battle to Them
If the party insists on resting before moving on to the next encounter, bring the next encounter to them. Instead of meeting that group of gnolls on the bridge, have the gnolls spot the party's campfire and seek them out. Instead of fighting the orc shaman in his dungeon throne room, have him run into the party while wandering the dungeon corridors. Instead of confronting the assassin in a dark alley, have the assassin break into the party's room at the inn.
Once players realize that over-resting has consequences, they'll learn to ration their combat resources.