If you're into multiday hikes it means you're stuck carrying multiday loads. It's a necessary evil. But carrying a big pack doesn't have to spell pain. They're designed to help adjust your load and improve comfort.
Problem is, it can be overwhelming trying to figure out which strap does what.
The key to a comfortable hike is knowing how and when to adjust your pack. When I go on a hike, I'm constantly tightening a strap here and loosening one there. By doing so, I rotate the pressure points on my shoulders, hip and back so that no one area gets overly sore. If you're stymied by your pack straps, check out this chart, which explains what straps to adjust when a certain area starts to hurt. As a rule of thumb, you shouldn't carry more than one-third of your body weight.