Even if you have canvas bags to use when shopping, they can sometimes be forgotten or if you are doing some spur-of-the-moment shopping you might not have them with you. Then you are often stuck using plastic or paper bags for your purchase.

To avoid forgetting bags, I put them in places so that they will always be there when I need them. I keep several in the trunk of my car, one in my backpack (which also makes a fine bag for carrying goods), on in my book bag, etc. This way even if I hadn't planned to do any shopping, or if I forgot my bags, there are also some bags available to use.