Tease him up with a ball, he misses, tuck that ball under the armpit and command fuss. A few steps of fussing, reward/tug/lift to out and repeat.
Czech dogs tend to be a bit suspicious, very aware of the surroundings and not real high in prey drive(I know, generalizing here!) so getting that engagement and focus takes some work.
I know if I gave my dog less freedom, more crate time, he'd probably be a different dog on the field, but I don't want to do the deprivation stuff either...would rather engage him and bring up the ethusiasm to work on my own.