I use SmartCalm on my mare and it works great! But if you don’t want to use a calming supplement, then you can try playing ground games before you ride. I always play Parelli games before I get on my mare to calm her down if she’s excited, and to get her attention on me. I also sometimes let her gallop around with me at liberty to let some of her energy out, but of course you can only do that if you have a field or arena to yourself. I highly suggest groundwork, though, and you should look up the Parelli games you can play with your horse!