-Keep as hydrated as possible, keep a water bottle with you, get cups of water from QS places (free!) also think about maybe bringing bottled water in since Florida water can be nasty
-Alter the outdoor stuff with indoor stuff, use the A/C as much as possible, walk through shops if you're walking down Main St midday, alternate something like Jungle Cruise with something like Country Bears that's indoors and a longer experience.
-Take breaks, take a sit down inside a QS restaurant to rest and enjoy the a/c
-Many outdoor kiosks for drinks have bins of ice out in the open to keep the drinks cold, on a hot day when I'm walking past I'll grab a few ice cubes and hold them to the inside of my wrists/neck to cool myself down
-There are those like, cooling towels, or ice pack style things to go around your neck to keep you cool.
You know your body the best, just keep it slow, keep it indoors alternating, and keep HYDRATED