I bring a satchel with me when I leave the house. I leave it in the car 99% of the time, but it has my sunglasses, sanitizer, umbrella, etc. in it. So, it’s helpful to bring along. I toss my keys in it and whatever the important thing is. If the important this is too big, I wrap the strap of the satchel around the thing or wind the strap around some part of it. I still forget things sometimes, but this has helped me significantly.