When a pickpocketer tried to pilfer my property while I was on vacation in another country, it wasn’t a surprise. I’d read warnings about the danger of subway thieves, so I knew what to do to protect my wallet. But I never expected it to happen.

Fortunately, the young man who grabbed my wallet had slippery fingers, so it fell to the floor where I could retrieve it. But the incident reminded me that I should have heeded the warnings.

We don’t like to dwell on warnings, because we think they’ll get in the way of enjoying life, but it’s imperative to…