Larry Bowa was the guy, who I thought should have been manager if Torre had to be replaced. I agree that motivation should come from within at this level.
I think the primary external source of motivation comes from teammates, particularly veterans.

Guys like Paul O'Neill, Tino Martinez, Bernie Williams and Scott Brosius were no hall of famers, but they came to the park every day and played hard and played to win. Jeter, Posada and otheryounger players in the mid-90s grew up in this environment. When all your teammates show up and take BP seriously, then you take it seriously; when your teammates dive for a ball or run into a wall; then you do the same.

The best I ever saw at setting the example was Pete Rose. He set the tone and work ethic of the Big Red Machine. He came to Philly and also won a championship. Mike Scmidt hit the nail on the head when he later said that Rose told him and others that the Phillie team was the most talented in the league, but couldn't be the best until they learned to be the best every inning of any game.

I'm not sure if this ties into the Cano thing, but if he sees Bobby Abreu avoid the wall and play as fly into a triple or A-Rod getting thrown out at second on a hit where he didn't go full speed, complacency might pass for acceptability.