Increase Strength by 2 and Constitution by 1 

You are a Beast

Your size is medium

Your walking speed is 40ft

If the horse moves at least 20 feet straight toward a creature and then hits it with a hooves attack on the same turn, that target must succeed on a DC 14 Strength saving throw or be knocked prone. If the target is prone, the horse can make another attack with its hooves against it as a bonus action.

You gain a proficiency in Athletics (If you already have a proficiency in Athletics, you gain an Expertise.)

You count as one size larger when determining your carrying capacity and the weight you can push or drag.

You have hooves that you can use to make unarmed strikes. When you hit with them, the strike deals 1d6 + your Strength modifier bludgeoning damage.

Being a horse gives you a connection to nature. You therefore have proficiency in one of the following skills of your choice: Animal Handling, Nature, or Survival.

You can speak with horses.