I'm right-handed and always put my rucksack on by starting with looping my right arm through the right shoulder strap. Yesterday my neck and right shoulder were a bit stiff and so I tried putting it on 'left-handed' i.e. looping my left shoulder through the left shoulder strap first. It felt very strange, I got all entangled up and nearly fell over. I'm wondering how other people might put on your rucksacks...maybe I've been doing it wrong all these years.