His diet sounds good, he's just a young silly boy, lol. Time and patience will bring him around. Just be really consistent. The time for "fun" and relaxation will be AFTER he's learned to stand quietly. When you have him in the halter, and you want him to stand still, get after him for ANY kind of movement. Carry a short crop with you if he doesn't respond to a jerk on the lead or a pop with the end of the rope. Pick a loud noise or word that means "quit that". I either say "Quit" or a loud "Aaaiihhhhh" noise. Don't say no, as it sounds too much like "whoa". When he acts up, jerk with the rope and use your word/sound cue. If he does it again, do both harder/louder. If he does it again, do both plus crop him on his shoulder. Whenever he gets out of position, move him back to where he was, jerk the rope lightly, and say "Whoa". Praise him heavily for standing still, use food rewards if he'll take them nicely.
Work on "Whoa" in the round pen and while leading too, so he understands that Whoa = STOP NOW. Teaching him to ground tie in the round pen can also really help.
Good luck and remember to have fun! The young ones are great, but they can really test your patience, lol.