I have a working springer and have been unable to teach him to relax. I find it waring.. think relaxing walk, picnic, watching birds, maybe a nap in the sun, camping, or working at desk, and he is always on the go!
Easy and fun to train - In his day he'd sit and stay for an hour while I left him to shoot bunnies and not move, or walk to heel at a glance and half a nod, and even try herding sheep (doesn't work, has no presence, but did follow my "away/come" commands and arm signals for direction. The happiest, most grateful dog in the world, but being in the presence of a coiled spring, who's just about holding his breath, nearly whining, because he wants to go, Go, GO, GO! is tiring when you want to do any of the things above.