Backpacks and proper fit and needs are as individualistic as shoes or boots. What fits and works for one person may not be right for you. Before purchasing, head out to the local gear stores and try out various packs. Most stores have different weights that will allow you to judge the fit and comfort level as a full 40 lb pack will fit and feel much different then the same pack when it is 1/2 or any 1/4 full.