I used to carry the gear I wasnt using (that part is important) in a camera bag and lug it around with me.. Lenses I'd never put on, filters I'd never use, more film than I could ever plan to shoot, an extra camera (or three) etc.etc... while leaving my main 35mm camera strapped on my neck. Well, as you could guess I rarely used the stuff in the bag. and I no longer bring a bag with me unless I am traveling more than 100 or so miles.
I carry my 35mm and medium format on my person with the one lens on each camera and a few rolls of film in my pockets of varrying types, some lens cleaner, 1 or 2 filters and if needed a tripod. I find this so liberating! To walk around and not have to carry a big bag and feel 'free' only carrying 2 cameras strapped onto me. For my shooting style, mostly urban, going minimal has worked out very well and I've never thought "I wish I would have brought......"
I thought "I wish i wouldNT have brought...." a lot of times while carrying all that gear I'd never use!