There are no legal ways. You offer incentives. That takes "make" off the table. Otherwise, you have no legal leverage. Are you suggesting illegal methods?
Your second sentence is just what I said. You offer incentives. You can't threaten with hygiene. Against the law. You can't lock them up in the dark. Alcatraz went the way of the dodo years ago. The food's always bad at best.
But, you can't "make" a prisoner do jack sh*t but serve his time. If he chooses to be locked in the hole 23 hours a day rather than bust his ass for someone's idealism, you ain't going to get a nickel's worth of work out of him.