Comment by JimBlackwood

For a breed that is partly bred to flush out game, throwing a ball is incredibly adrenaline inducing and will not tire them out - they’ll just keep going till they fall down. Working cockers are one of the breeds susceptible to exercise induced collapse, albeit rare it shows how insanely motivated they are.

To get them tired, you need to chill them out and have them use their brain and/or nose.

Maybe try some sniffing games, sit down during the walk and have them just take in the environment, do some obedience that makes them think, or throw their food in the grass and have them figure it out.