I'm often reminded of the movie, Network, which many of you may have been too young to see or to remember. The defining moment of the movie is when Peter Finch as Howard Beale sticks his head out the window and screams, "I'm mad as hell and I'm not going to take this anymore." Almost in unison, from every window in the neighborhood, others join in the chorus. The statement is a contagion, and anger expressed is, in fact, contagious. It spreads with its own momentum. Once out of the bottle, it is difficult to contain.

All leaders should be wary of using anger. Your anger and passion may get you on first base and move your agenda forward, but if you're not careful, you may reap the whirlwind.

So here we have Donald Trump and Bernie Sanders. Clearly, they have struck a common chord. They are both worried about, among other things, the conspiracy of elites, incompetency of bureaucracies, and the unevenness of competition. Sure, they differ in some of their policies, but in their underlying appeal--in that voters are mad as hell and won't take it anymore, they are essentially the same candidate.

They both learned one fundamental trick that many leaders learn--for good or for bad--to appeal to a sense of deprivation and neglect. To appeal to frustrations and make promises.

But the question remains, how do leaders convert a whirlwind into concrete policies? Like many charismatic leaders with dramaturgical appeal, their challenge will be to execute. The problem is that the very appeal they have now has the potential to alienate those moderate mid-range partners they will need to move toward concrete results.

Revolutionary leaders, by their nature, alienate as many, if not more, than they incorporate. As a result, they may lose their legitimacy with the mainstream actors that they need on their side to move their agenda forward.

Don't underestimate the resentment of the middle ground. Most people aren't revolutionaries and they aren't traditionalists. They prefer to take it one step at a time, make adjustments when necessary, and develop plans when they have to.

There may be a new silent majority out there, concerned with making adjustments rather than revolutions, less angry than Donald and Bernie may think. This silent majority may become disenfranchised, which may make policy execution almost impossible. When the reality of execution hits the fan, it will be difficult to put Humpty Dumpty back together again.

Obviously, passionate rallying of support is a critical leadership skill and an important skill for leaders to develop. Donald and Bernie show that passion and perhaps a tinge of anger can be a powerful mobilizing tool. But we should take pause. Leaders must deliver on their passion and promises. They have to remember that their emotion may push away the moderate core they will need on their side when it comes time to execute. The leadership lesson is to keep your passion and rhetoric in check in the short-term to assure long-term success.