Do you buy 'bags for life' and then find you don't have one on you when you are out shopping?

Have you discovered those bags made from very thin, light material that scrunch up and take up almost no room in any small bag you might use for keeping essential items when out and about? Where do you keep the more substantial bags? If you shop by car, do you keep them in the car? 

Why not make 2025 the year you never buy a disposable plastic bag to carry your shopping.