Here's a practical tip to lighten your load.

Train with a heavier load than you will be hauling in the field.
Have trouble finding motivation to simply train?
Park a designated distance from the grocery store. Ie, a public park. Take your pack to do your shopping.
Haul it back to the vehicle or home.
Get into a routine and you'll be closer to your fitness goal.
In the field, your load will feel lighter. Chances of injury reduced.