It's time to applaud sunscreen, the unsung hero that stands like a dedicated bodyguard keeping your skin safe from the relentless sun. But the hero's shield fades with time. So, to stay befriend 'lifesaver lotion', you must understand its 'use and reapply' mantra inscribed deep within its invisible SPF armor.

Our relationship with sunscreen is quite the summer fling, isn't it? A bit of sun and we're slathering and slopping it on our faces and bodies. But as our favorite parasol with a pharmaceutical twist, sunscreen needs more than a one-time application during the day. It's like a marathon runner needing water throughout the race, not just at the start.

The sun, while necessary for life and great for beach parties, throws UV punches that can leave your skin bruised with sunburn, early aging, and worst of all, cancer. Annoyingly, this heavy-hitter doesn't take a break even on cloudy days.

To mount an effective defense, you need to leverage sunscreen's secret weapon: reapplication. Just as UFC fighters freshen up between rounds, your skin demands regular sunscreen top-offs to continue keeping UV jabs at bay. Remember, 'once is never enough' when it comes to sunscreen.

And don't be stingy with it. Dermatology boffins propose a generous 30ml (about a shot glass full) as the magic amount to give your skin a proper SPF shield. Miss no spot, especially those hide-and-seek friends like your ears, neck, and the back of your legs.

Now, talking about SPF (Sun Protection Factor), it is not an 'apply-it-and-forget-it' deal. Even a sunscreen boasting SPF-100 doesn't mean it will guard you all day long. Evil UV rays are too potent for that. No matter if your sunscreen's SPF is akin to a fortress, all sunscreens need re-oiling every two hours.

In this battle against the sun, make sure you've chosen a broad-spectrum sunscreen. These double agents combat both UVA (the ageing villains) and UVB (the burning bandits).

So, next time you find yourself facing the sun, gear up to reapply your sunscreen like a pro. Show that blazing ball of fire who's boss, and remember this mantra - 'Apply, dry, and reapply; this is not a bloody SPF lie.'