The forecast is perfect—84 degrees, mostly sunny with only a 2% chance of precipitation. The beach chair is unfolded, the paperback is starting to get good and I'm ready to swap my pasty winter-white skin for a bronze glow.

Except the UV-tracking jewel on my bracelet keeps forcing my iPhone to disrupt my favorite sedentary sport. "Apply SPF 15," my phone flashes after a loud chime. "The UV Index has hit 7," it says moments later. Just like my parents at the community pool years ago, the pair keep interrupting...