Reapply sunscreen every 80 minutes when swimming or sweating.

Every 80 minutes, assuming your sunscreen is labeled “water-resistant.” That’s the standard. If it says “very water-resistant,” you get 80 minutes. Some only claim 40. Check the bottle—it will say.

Here’s the thing: water and sweat rinse sunscreen off faster than you think. Even the good stuff breaks down. You can’t feel when it’s gone. By the time your skin turns pink, it’s too late.

Set a timer on your phone. Reapply after 80 minutes in the water or after a big sweat session. Don’t trust “once and done.” That’s how you get a sunburn halfway through the afternoon.

Your future self will be grateful you didn’t skip it.