Don't work yourself past your limit, take a minute to breath and cool off regularly. Drink a lot of water before during and after being at the barn. Also ride in cool clothes, find breathable pants(I like the kerrits with the grips), and I also really like lululemon shirts, they wick away the sweat and cool you off.
Freeze a water bottle or two the night before you go to the barn and take them with u so you have cold water to last you most of the day.
Drink lots of water. I use a cooling vest when I'm riding and sometimes wet my cross country vest.
Always bring water out to the ring so your staying hydrated. Also when your done riding take a moment to sit down in front of a fan and have some water. Also frog togg towels are very cooling.
Get some mesh gloves from noble outfitters so you're hands don't get sweaty
Cooling Towels - Best For Any Sport Activities - Athletes Cold Towel
Get one of those mist bottles and put ice water in it
Bring water and drink a ton!! Also maybe invest in an ice fil shirt? The lower body tenparure
During summer camp, we hose the kids heads off with cold water (or just at the base of the neck) before they ride to keep cool
Maybe invest in a fan? Or I often bring those kids juice boxes froze but so when I finished my ride they're very cool and slightly melted, really good idea for shows int he summer! Also how ventilated is your barn? Maybe tack up outside in the shade like near a tree. Also horses feel the heat too so make sure he's getting enough salt/ electrolytes in his feed and drinking enough water
Ride early or late or if you have to ride when it's hot then wear riding tights and stay hydrated
ride early or late in the day! i really like gatorade because it has electrolytes or something. also, misting water bottles are great!
Buy a wee mini fridge and keep it full of water bottles
Stay hydrated and if you are outside being a water bottle with you! Were thin clothing
Drink lots and lots of water, if possible ride when it is later and cooler, take breaks while riding and stay in the shade, make sure to wear ventilating clothing.
Drink water and avoid being at the barn for the hottest part of the day if you can (usually between 4-6pm)
I try to ride later in the day or early in the morning when it is cooler rather than in the middle of the day.
I have this towel from equi cool down. It really helps me.