A fully loaded backpack can get pretty heavy, so follow these steps to get it from the ground to your back more easily:
With you standing and your pack sitting upright on the ground, use one hand to grab the pack's haul loop. (That's the webbing loop on top of the pack.)
Using a wide stance with knees bent, slide the pack up to your thigh and let it rest.
Steadying the pack with one hand still on the haul loop, slip your other arm and shoulder through one of the shoulder straps, pushing your shoulder in as far as you can.
Without any abrupt or jerking motions, lean forward and swing the pack onto your back and slip your arm through the other shoulder strap.
Buckle the hipbelt first, then stand up straight and cinch down the shoulder straps. Adjust the load-lifter straps (located at the tops of the shoulder straps) to pull the pack inward. Lastly, buckle the sternum strap across your chest.
Whenever you're ready to take off your pack, it's easiest to loosen the shoulder straps in addition to unbuckling the hipbelt and sternum strap.
Tip: As you hike throughout the day, slightly vary the tightness of your hipbelt and shoulder straps to help your hips and shoulders feel less fatigued.
Is your pack too heavy? See the REI Expert Advice article, Ultralight Backpacking, for our tips on how to lighten your load.