I finally started using a canvas bag when I go shopping. I had some here and there, but then I found one for a dollar at a Farmers Market in South Bend that was roomy and easy to carry and fold. It turns out they have a neat website: see what a difference you can make just one bag at a time! 1bagatatime.com
Sometimes the folks at Meijer think I’m odd, but mostly they don’t mind that they don’t have to do the bagging. Meanwhile stores like Trader Joe’s and Wild Oats will enter you for a gift certificate drawing, take money off your order, or donate to charity when you reuse a bag.