How is he kept? What is he fed? What sort of exercise does he get prior to you asking him to lunge? How has he been trained? Being a 10yo DWB doesn't explain anything. If he's jumping out of his skin from too much feed/too little exercise &/or you or he haven't learned how to lunge basically, there's no way I'd consider using side reins or lunging with a bit.
I agree my KWPN is a big LAZY boy but I'll tell you he is BLOOMING under the hand of my new Dutch trainer. But on on topic ....
What they eat and how they are kept (stall kept or pasture) ALL that stuff is very important.