One big thing Barack Obama has learned about being president? The job isn't as powerful as you might expect.

In an interview with Bill Simmons in 2015, which is well worth reading in full, Obama explained that he "didn't fully appreciate" how "decentralized power is" in the US political system until he took office.

That is, to get anything done, he had to spend a ton of his time trying to persuade other people. Here's what he told Simmons:

OBAMA: What I didn’t fully appreciate, and nobody can appreciate until they’re in the position, is how decentralized power is in this system. When you’re in the seat and you’re seeing the housing market collapse and you are seeing unemployment skyrocketing and you have a sense of what the right thing to do is, then you realize, "Okay, not only do I have to persuade my own party, not only do I have to prevent the other party from blocking what the right thing to do is, but now I can anticipate this lawsuit, this lobbying taking place, and this federal agency that technically is independent, so I can’t tell them what to do. I’ve got the Federal Reserve, and I’m hoping that they do the right thing—and by the way, since the economy now is global, I’ve got to make sure that the Europeans, the Asians, the Chinese, everybody is on board." A lot of the work is not just identifying the right policy but now constantly building these ever shifting coalitions to be able to actually implement and execute and get it done.

Of course, that's right — on a great many issues, the president isn't the policy-wonk-in-chief, he's the coalition-builder-in-chief. And without a strong enough coalition, he can't get his way. This is true on issue after issue — from gun control to the cap-and-trade bill to immigration reform.

This is a common realization that presidents have after taking office. Indeed, it's so common that political scientist Richard Neustadt wrote a book about it decades ago, in which he made the famous argument that at its heart, "Presidential power is the power to persuade."

Now, Neustadt didn't just mean that the president has to rely only on convincing people with the power of his words. Instead, the president is engaged in a long bargaining give and take with all of those actors Obama listed. The president's position, prominence, and powers provide many advantages in that process. Still, of course, presidents often fail to get their way — and even when they do get what they want, they feel like they're working awfully hard at it. Neustadt quotes President Harry Truman complaining:

"I sit here all day trying to persuade people to do the things they ought to have sense enough to do without my persuading them. ... That's all the powers of the President amount to."

Indeed, Obama has chafed against these limits so much that he's pushed the limits of his executive authority in some novel ways, as I described in 2014. But even here, he has been hemmed in by the courts — for instance, his major immigration executive actions were blocked.

So the president's difficulty getting his way is a persistent feature of American democracy. And Matt Yglesias has argued that it could eventually lead to the doom of the American system — if this usual bargaining and persuasion process breaks down due to increased polarization, presidents will stretch the limits of their authorities ever further, leading to an eventual constitutional crisis.

For now, though, Obama's realization will be familiar to other presidents. As George W. Bush once said, "If this were a dictatorship, it'd be a heck of a lot easier."