How come with all the brilliant thoroughbreds
That stand strong and ready at the starting gates
Those glorious, shiny coats gleaming in the sun
Do I keep on beating dead horses?
Instead of placing my bets on the alive and thriving?

Don't I want to finally engage in the race?
Don't I want to to keep my eyes on the winning prize?
For a dead and decaying horse,
With flies swarming about its lifeless carcass
Just ain't gonna move

Dead horse beating is a ludicrous hobby
It is more futile than leading a thirsty horse to water that just won't drink
That whip, in hand, just needs to be surrendered, put down on the ground
As well as finally releasing, letting go, on the pulling of those reins
So that horse can finally have a proper burial

Be finally laid to rest

In my dictionary
Dead horse (a noun) = people, places, or things of decay that should be out of your life
Dead horse beating (a verb) = from your thoughts to your actions, trying to revive a lost cause
Dead horse (synonoms) =  bad relationships/friendships/acquaintances {that are of the morgue}

Anything that is counterproductive to your life