You can fiddle with your pack, or lighten your load.

I carry a hammock and tarp or single man tent- or sometimes just a tarp. The hammock is more comfortable but heavier.

I bathe every few days (or more frequently) by either taking a dip, or a washdown in my little pot using a liner sock like a sponge bath. - I often take a wet wipe per day on shorter trips.

I hate filters, and nasty tasting chemicals. I use chlorine dioxide drops - doesn't break, doesn't taste, and a lot lighter than a filter.

If I'm using the little bitty tent, and 3/4 length pad, all my gear without water and food and fuel weighs about 10 pounds (for normal season backpacking, not winter). If I take the hammock and tarp instead I often end up around 13 to 15, depending on the hammock (ok I have a few of them)

My shoulders aren't sore, because I'm carrying somwhere between 15 to 20 pounds total for a weekender, typically. my starting weight for a week on the trail is about 28 pounds.

my backpack weighs a little over a pound

The point is, if your shoulders are sore, lighten up. if you're cold, get a better pad and bag. both those will lighten you up considerably. (and your wallet, esp. the sleeping bag)