Use a cowstail or personal anchor system to connect your pack to your harness. You can then hang your pack below you while you chimney, bridge, or stem.
Hanging your pack frees up your back and hands so you can put your back against the wall while chimneying.
Because the canyon is usually narrower closer to the ground, packs can often get wedged between the walls. This make you spend a lot of extra energy to drag your pack along. It also causes a lot of damage to your pack.