Can't fight, climb a monster nor carry stuff? Arisen jogs like a turtle and his Stamina drain is astronomical while running? He must be Overencumbered!
There are ways to deal with encumbrance, let's start from the basics.

I know, all those things you carry are necessities or valuables, but how about store some of those in a safe place? Yeah, there is a storage for your belongings, at the capital's most notrious inn, Union Inn. Asalam, the owner, apart from offering an educative services and accomodation, provides storage space.
Actually, every innkeeper around Gransys ti Asalam plus:
- Ecbal, his twin from The Encampment
- Pablos of Pablos' Inn at Cassardis
- and even not-much-of-an-innkeepers Olra and Barroch at the Bitterblack Island
offers a shared storage space. And one has acces to all one stored at every inn.

But that's not all as there are couriers scattered around Gransys. All those fine, hearty, backpack carrying lads offer is nothing else but a transport service: they station at rest camps and will make sure one's deposit reach the storage safe and sound.

Above all else, if one necessarily has to carry some serious load, why not control the amount of time one is burdened? Set up a Portcrystal at one of the rest camps to be able to get rid off of all surplus: no need to carry around Gransys anything but worn equipment plus few necessary tools and curatives.

Wait, wait, wait a minute! You thought that was all? Well, you thought wrong as, actually, Pawns, your travel/battle companions, can carry items for you...you knew that ...already?
And did you know that Support Pawns (those are the Pawns you hire, your is called "Main Pawn") you'd load your things on and release will put those things into a Storage? Yes, if one really needs a courier and there are Pawns or Riftstone nearby one just has to put all excess items into Pawn's Inventory and either release it or make it "die". Just don't do this to on-line Pawns or they'll get mediocre ratings (but hey, everyone "hired" Rook at some point, right? ;).
Naturally, one can't get rid of certain items this way, but those are merely a drop in the sea.

With the above in mind, the equipment one wears/uses still contributes to a total encumbrance value and the main factor here is not just the type, but also a quality.

So, another step in everlasting perfection of one's encumbrance level is thinning up one's equipment as, generally, the Enhancing makes it lighter. That's why one should enhance one's rags and shivs as often as possible not just cause this'll become better, but also due to weight loss. A win-win IYAM.

Good NPCs that offer this service are:
- Caxton, of Caxton's Armory at Gran Soren
- Reynard, the Gransys travelling peddler
- Mathias, temporarily settled peddler of the Greatwall Encampment
- and finally/ultimately Barroch, the vagrant Arisen of Bitterblack labyrinth.

One may also be interested in increasing one's encumbrance limits. One can achieve this by picking the right Augment.
To be specific, by picking a Fighter vocation and advancing till Rank 5 as his Sinew Augment will allow carrying 20 kg more without hampering Arisen's/Pawns' moves. There are also specific gear pieces, among Bitterblack armors that give similar bonuses, but I consider those merely an option - also they are an end-game content (and mostly look awful).

Finally, there's a choice of things to carry.
Obviously a Ranger won't have much use of Physical Defense boosting curatives and Wyrmking's Ring, while a Sorcerer of Blast Arrows and Strength boosters. Some characters need more healing, some more Stamina curatives ...and some don't...

There is a matter of area too:

• No need to bring much curatives to South Gransys when there are apples and grangrapes around.
  
• Why bring heavy Flasks of Oil or Water when there're water and oil bowls around? Bring Empty flasks instead.
  
• Why bring Stamina curatives into a Saurians' fight? Severed tail is all one needs.
  
• Why bring many healing potions to Bitterblack when there's an abundance of Kingwarish here. And actually top notch Harspud pots drop around like crazy!
  
• Why carry Light-Cure around Bitterblack if Lunanise grows there? 'Tis the same.
  
• Don't need much Stamina curatives at Midnight Helix as there're piles of sour meat right by the entrance.
  
• Not even mentioning Bitterblack Sanctum's infinite supply of curatives. Whether it's a glitch or conscious design choice, I don't know, the fact is the three congeries of pots at the narthex area of the Sanctum resuply every time one reenters the area. And they drop everything one may need during the upcoming boss battle (apart from Magick boosters): Harspud potions, Large Nuts, dryed Harspuds, Conqueror's Periapts, Light-Cure, even Panacea.

But there's more to it. Since one can actually combine resources on the fly in Dragon's Dogma, why not be picky about those too? It is good to know some useful recipes:

• Need a Flask of Oil for a Lantern? Carry an Oil Arrow and an Empty Flask. 'Tis much lighter.
  
• A Beech branch and Flammica weight above twice less than 5 Blast Arrows. Swap Flammica to Throwblast and you get even more benefits.
  
• A Burst-Rock and Flammica weight less than trio of Dragon's Spits. The same is true when it comes to Lava Rock and Flammica vs 3 Throwblasts.
  
• No need to bring loads of Oil/Poison arrows to the woods when there's plenty of branches to be gathered around. Just bring some sour meats/Flask of Oil or poison mushroom/Poison Flask and combine with what you'll gather. And it gets even better if Boars or Spiders are around!
  
• Battling Goblins or Saurians? If carrying some Nightcry against poisoning you can combine it with Wormwood Sap (goblin drop) to get Desiccated Herbs.
  
• Visiting Barta Crags or Everfall? Bring Scarlet Angelica in turn - against poisoning, but also to combine it with Forgotten Arcanum (Skeleton Mage drop) or Blood Decanter (Grim Goblin drop) to get a powerful Salubrious Brew.
  
• Hunting Wolves or Harpies and need Stamina curatives? Backfat Oil is what you need. Bring some Hunks of Ore (very light) and combine with Sour Scrag of Beast that'll drop often.
  
• Why exactly one would need to bring Panacea to Bitterblack if all one has to do is to combine an Interventive (drops from breakables there) with Lunaninse (grows there)? At worst one can make a Light-Cure by combining Lunanise with a Flask of Water.
  
• There's this wonderful ingredient, Violet Concoction. A product of combining Crimson and Cerulean concoctions (those come from combining Destiny/Anathema Grass or mentioned Nightcry with other plants, check DD wiki[dragonsdogma.wikia.com] on how to make those). This one weights next to nothing and makes miracles. Combine it with single target curatives like Secret Softener, Purifying Brew, Dose of Strength or even Acid Sac (Geo Saurian drop) to get group version of given curative (or single target all-star-curative Panacea, from Acid Sac).

and so on, and so forth. By gathering all kinds of resources and combining them you'll learn more like those. Or just check out Dragon's Dogma wiki ;)

Those are just the basics, based on my experience/s and Dragon's Dogma wiki info. But one should always watch carefuly and learn new ways of making one's Inventory thinner. Keep fit!