Reduce Wallet and Keys for a trip – up to a point:

When I go on a (several day) trip, I thin my wallet and keyring, leaving home things I’d never need on the trip, like my local library card. But here’s what’s important: if you can’t remember what some of the keys on your ring are for, even if you haven’t used them for a year, take them with you! Otherwise (as Murphy’s Law implies) you’re going to remember what they were for in the worst possible way.