I couldn't bear carrying all the stuff around most of you do. I never carry a bag. All I need when I go out is a wallet, keys, phone, a pen and a white cotton handkerchief and they all fit in my pockets. I guess it helps that I usually have a proper jacket on, so the inside pockets can take the wallet, pen and the phone, leaving the keys and the hanky to my trouser pockets, but still... if I don't have a jacket, I don't take the wallet, but just take out the 2-3 cards I'll need that day and some notes, and put them into a slim credit-card holder, and take the phone out of its case. Then everything can fit in trouser pockets.
I just hate carrying stuff around. I even reduced my (already fairly limited) wallet contents out recently, so as not to carry around some loyalty cards for places I hardly ever go to.