Sun off snow and water catches people out
A lot of people protect against direct sun but forget reflected UV. Snow, water, and sand bounce sunlight straight up onto your lips, so a ski day or a day on the water can hit harder than midday in a park. If you have been caught out by reflected sun, where did it get you?
Learned that one the hard way on a lake trip, I was so careful about sunscreen on my face but totally forgot my lips and paid for it a week later. Now anytime I'm near water or snow my lip protection goes on before I even leave the house.
Oh this got me last spring on a ski trip, I was so careful all winter and then one sunny afternoon on the slopes undid everything. Now I just assume any bright day near snow or water counts double and slather my lips way more often than feels necessary.
Oh this got me on a lake trip last summer, I was so careful about my face but totally forgot my lips and paid for it a week later. The glare bouncing off the water really is sneaky, now I set a phone reminder to reapply because I know I'll forget otherwise.