Clean up after yourself in a store

Retail workers don’t appreciate having the extra work, no matter how many “That’s their job!”s your douchey friend may have used as justification for making a mess in a store. If you don’t do these already, the next time you’re in a shop, put the clothes back where you found them, take the shopping cart to the dedicated space for them, or place that Woody Allen book back in the film section, rather than the crime section just because that’s where you’ve ended up and can’t bother expending the extra calories it would take to walk back to "film". You’ll burn about 3 or 4 calories (not exact figures) and avoid evil glares as well!

Effort involved: an insignificant amount.