Totally feel that. Sunscreen needs a re-up every couple hours, no joke. Learned the hard way after a beach day where I got fried. Sweat and water wash it off so fast. Now I stash a small bottle in my pocket on hikes. Saves you from looking like a lobster later.
My buddy figured one coat of sunscreen would cover him for a full day at the lake. He was bright red by the afternoon and in pain for days. Now he never misses putting more on every two hours.