San José, like many other cities (especially those in California), has banned the use of plastic shopping bags. That means that when you go shopping, you need supply your own bag(s) to carry your purchases. At the grocery store, a bag is essential, especially when you're shopping for more than a few items.
But remembering to bring the bags into the store with you is a pain. There you are in line at the cash register, and you suddenly realize your bags are still in the trunk of your car. (sigh)
If you have an iPhone, you can use location-based Reminders to help prevent this from happening to you. Next time you're at the grocery store, just add an item that reminds you to bring your bags along when you arrive at the store. To do this, open Reminder, click + (plus), then enter the reminder. Tap Done, then tap the reminder you just added and change it "when I arrive" at "current location." The results will look like mine, below.
The next time you get near the store, iPhone will remind you about the bags. To keep the reminder active, so it continues to work for future visits too, don't mark it as completed. Eventually, after you've developed the habit of bringing your bags, you can check it off and rely on your own memory instead.