Originally posted by tilling To top it all off, I'm using a Canon 10D right now, so it's both heavier and more leveraged than, say, a Pentax DLSR.
Don't want to be a Canon basher but you've hit the nail on the head here on one of the main reasons to shoot Pentax, and the new K7 is even more user friendly and manageable due to its low weight and small footprint.
This is one of the reasons I held off buying a DSLR for so long since I was so used to carrying around my LX and everything I tried just seemed so big and clumsy and not manageable. However, with the money you'll save from switching from a heavy 'pro' Canon to a lighter Pentax you'll have to reinvest the difference in a gym membershp so your muscles don't atrophy
But seriously, whatever camera you use, especially if you are using MF lenses, hold the camera and controls in your right hand and put the palm of your left under the body/lens and adjust the focus with your left thumb and forefinger. That way your left hand is supporting it. If the weight is an issue dig your elbows into into your belly so your arms support the weight with your skeleton rather than your muscles. Another trick I used to do is to wrap the neckstrap around my right arm and elbow in such a way that it leveraged my right arm to hold some of the weight due to my skeletal structure also.