yeah, a manager isn't dad. you don't get to patronize your employees, who are ultimately your equals, and upon whom your performance is (or should be) measured. you hafta work through them to justify your existence.
when productivity falls, you make a plan. you demonstrate an understanding of a problem, present the changes, give the orders, and accept as much feedback as you can without paralyzing the solution. when people need to be told to shape up, you say that and you tell them specifically what needs to change and why. stories from ol' grand-dad are unnecessary, unless you want to be the butt of endless behind-your-back mockery. when people succeed, you give them all the credit. if they're good employees, they'll share that credit with you.
but man, it's so easy to be a bad manager. drop the vigilance and allow yourself to become lazy, and the self-justifications start. no matter how well you think you're pulling off the excuses, your employees are probably as smart or smarter than you, and will see through it in a heartbeat. it's scary!