This is a great life hack that's so simple and brilliant: put one of your shoes in the hotel room safe when you travel!
This comes from The Daily Mirror's Travel section, where a flight attendant Esther from the Dutch airline KLM said that it's an easy way to not be forgetful. She said that you should put your valuables in the shoe, like your passport or license or credit cards, and when you're packing your suitcase to leave, you'll remember where your missing shoe is. See! Simple and smart!
Also, a Mike Jones tip: let's use a different number than 6969 for the safe code. I do it and so do quite a few of my friends!