No one has answered this part of the initial question.

I wonder, does anyone here also engage in any sort of physical preparation, strengthening muscles, physical fitness.

Many double rifles are quite heavy, particularly in comparison to a 'normal' rifle. People always exclaim when picking up my .450 as it is heavier than needs to be at around 13 lbs.

In the field with a proper sling, and I do use a sling, a webbing one with padding, which is very comfortable, I don't really notice it, until my shoulder actually starts to hurt. I tend to carry my rifles mainly on one houlder. And I learned from experience that ache in the field may last for days if shoulders are not switched enough.

So what do the USERS and HUNTERS with double rifles here do to prepare for the actual hunt? Maybe perfectly physically fit from one's daily life perhaps?!