Make sure your carry capacity isnt in red. The more items you have the heavier it is so your characters get tired faster.

Also this game is based on D&D/pathfinder so it's only normal that after hours/days of traveling your group would get tired.

When you rest make sure you have rations and go to 'manage' your rest setup. Make sure you check 'Use Rations'. This makes resting MUCH quicker. If you're that bothered about the resting scenes, rest on the world map where you get no scenes, BUT you will not get any character related and important dialogs, like character quests and romance options while resting on the world map.

Another factor that makes pawns complain about resting is their constitution. If it is low they will get tired very quickly.

You have to rest everyday, so it only makes sense your characters do too :)

Kidding aside, there are some items and feats in the game that will help with this. Fatigue can happen from resting in medium or heavy armors. To combat this you can take the Endurance feat on characters that use heavier armors. Also, low CON stat effects how fast your characters tire. So feats and items that boost your CON will allow you to go further. Lastly, off the top of my head, an item like 'heart of ira' (Found in a crate in Varnhold) makes your character immune to fatigue.

Hope this helps some.

Thanks!
All of you came with alot of helpful tips!
I'll aply them as soon as possible, I just wasn't aware of the things you pointed out. It'll help me enjoy the game even more :)