I bought my first yearling about 3 weeks ago. I let him sit and get used to his new home and have just been grooming and picking his feet and working on basic manners. My previous riding instructor told me to try trotting him on a lead to check for lameness so I attempted it. He's great at walking and stopping on a lead but he flat out refuses to trot. About two days ago, I finally got him to trot beside me a little, but he got waaaay too excited and ran ahead and bucked. He ended up kicking me in the hip while he bolted by, and now i have a decent sized hematoma. I never expected him to react like that. He has never tried to push me around in any way, he always respects my space in the pasture, he rarely gets spooked, lets me touch his behind and pick up his back feet. He's a little mouthy and tries to chew on my shoes but i correct him and he has never tried to actually bite me in anger or frustration. He's really sweet and this just took me by surprise. I'm not sure that I handled it right afterwards. When I got up, I felt that it had been too long and the opportunity to correct him passed so I just walked him around and put him back in the pasture. I tried to get him to walk on a lunge but when i ask him for a simple walk, he starts galloping around me and bucking and kicking in air. I have no idea what to do. Some people told me not to lunge him at all, and others have told me to lunge him at a walk so that he gets the idea before he gets too big. I have no idea what to do and honestly, I'm scared to even attempt to lunge him again. Should I just wait until he's around 3 years old? Is he trying to hurt me on purpose or is it him just being playful and rough? I don't want to cause any future behavioral issues.