How do you thank someone that has been so good to you? ?

At the weekend I had a parade with sea cadets and we were using rifles. We had to do about a fifteen minute march holding the rifles in the same position the whole way, I could hold my rifle any longer cos my arm wouldn't take it ne more but the 2 adults that wer ther just td me to get on with it basically and then we went into the ring and were bout to do a display but o was in tears then one of the adults come over to me and took the rifle off me for a bit but the gave it bak and made me start the rouitne and then I was crying agen half way thru and it took 1 of the instructors who weren't doing the parade to come and take the rifle off me and pull me out. How do I thank him enough??