Kits for Activities
Pack a bag. Maybe two bags, with a shared backstock and standard checklist.
Hobbies, sports, volunteer activities, art-making, and family adventures are (typically) structured pursuits. As such, the items required to perform them are clearly distinguished and readily enumerable.
Enumerate them explicitly. From this known inventory, develop a standard kit of materials which you always take with you to that activity. Keep those materials in a unique bag, and make the checking and restocking of it routine. Create and print out checklists. Consider creating multiple backup copies of the physical kit, ready to go. At scale, you may need to implement a pull system to reorder backstock.
An example (a packing list for a short trip) can be found here.