As Samuel L. Jackson might have asked in a TV commercial, "What is in your wallet, MOFO?" Some day the majority of people will do everything with their smartphones and may not carry a wallet any more. For now, most of us still do and sadly, sometimes the wallet get lost or stolen.
I read a tip a long time ago that said we all should regularly lay out the various cards we carry in our wallet and photocopy them for record-keeping. I know, photocopy, I said it's an old tip, didn't I? These days everything is photographed by the smartphone, like I just did below. Of course yours won't have the white rectangle when you do it. Yes, I have many more items in my wallet, but the four shown are enough to illustrate the point. Yes, I like reward accounts.
The idea is to have all the important info from the cards in your wallet in a convenient location. You would have the cards laid out, snap a photo, then flip them over and snap the other side. Ten cards per layout may be the optimal number. Should the unfortunate thing happens (your wallet is lost!), you would go back to these photos and call your credit card companies etc to cancel the accounts or update them on your situation. Sure you can be more diligent and create a spreadsheet, or something better, to track your wallet, but I am sure snapping photos works best for most people.
It is probably best to print out the photos you took and keep the prints in some safe location at home. If your wallet is stolen, the smartphone may be stolen along with it. To be extra safe, delete the photos from the smartphone, or whatever camera you used to snap them, no chance the info is gleaned should someone play around with your phone.
May your wallet be with you for a long time!