Sometimes , there can be too much of a good thing. Take the frequent advice from politicians that Americans should go about their daily lives without obsessing over terrorism.

That was one of President George W. Bush’s early responses after 9/11, when he said the terrorists would win if we let fear control our lives and change our behavior. It was the right idea at a time when the nation was in danger of succumbing to paralyzing anxiety over the worst attack in history.

In the years since, the counsel to live normally has been repeated endlessly, to the point where we follow it to a fault. Now we seem to believe that terrorism will go away if we ignore it. All we have to do is send a few drones to kill a handful of bad guys in far-away places and we’ll be as snug as bugs in rugs in the good ol’ USA.

That belief falls somewhere between an illusion and the Big Lie. In truth, the threat of terrorism here at home and around the world is getting worse by the day. So much so that almost nothing else matters in comparison.

Yet from President Obama on down, we are, with too few exceptions, deceiving ourselves by refusing to recognize the changing reality. Islamist groups are seizing power and territory, and neither wishful thinking nor denial will make them stop. They aim to hit America, and we must stop pretending that 9/11 will forever remain unique. It, or something worse, can happen again.

Even while we digest the horror in Paris and continue to debate whether Obama should have visited to mourn, new atrocities dominate the news. Just the other day, the Islamic State executed 13 Iraqi teens for watching a soccer match on television, and threatened to behead two more hostages unless Japan paid a ransom of $200 million.

Most troubling, rebels took over the presidential palace in Yemen Tuesday, putting yet another Arab country in danger of becoming a jihadist haven.

Yemen is an American ally — we gave it $1 billion in recent years — that sits next to Saudi Arabia and is one of four countries that peacefully replaced its autocratic leader in the misnamed era known as the Arab Spring. The bloody chaos in the capital of Sanaa should end any fantasy that the Arab world is making even minimal progress toward democracy.

As The Wall Street Journal put it, “Yemen could become another Afghanistan — a failed state dominated by warlords and extremists.”

There is more bad news, too. Israeli intelligence reportedly believes that Iran and Hezbollah are preparing to invade the Jewish state, and the White House has given up on forcing Bashar al-Assad to leave Syria.

So much for red lines over the use of chemical weapons and Obama’s tough talk that Assad would have to go. What the change means for our policy of training Syrian rebels is anybody’s guess.

By the way, are we still fighting the Islamic State, or have we given that up, too? And exactly when will Iran get the bomb?

To be sure, terrorism is not an existential threat to America the way it is to Israel, at least not yet. But the proliferation of lethal weaponry, combined with a competition among terror groups to see who can strike America first, puts us in the permanent cross hairs. And it is chilling that a growing roster of intelligence officials publicly say that homegrown attacks like the ones in Paris are inevitable here.

We are running out of time. Of course, we should go about our lives and not cower in fear, but we must never forget that we are still at war, whether we like it or not.

Although Albany has a $5 billion surplus thanks to legal settlements, the most important battle this year involves education. The first shots already have been fired, with teachers unions swatting away talk of more charter schools and tougher teacher evaluations. Instead, they demand that Gov. Andrew Cuomo show them the money.

“He has declared war on the public schools,” Karen Magee, the president of New York State United Teachers, told The New York Times.

“I’ll be happy to stand with the teachers, the students and the parents if the governor wants to have a war,” she added, saying, “I’m more than confident that we will win.”

Magee’s ridiculous rhetoric about “war” and preening bravado notwithstanding, the unions are in a deep hole of their own making.

They didn’t endorse Cuomo, because he supported charters and spending caps in his first term, and spent millions in an unsuccessful bid to keep Republicans from controlling the state Senate.

That puts them on the outs with two of three power centers. Even their one friend, Assembly Democrats, must decide how much capital to waste defending the unions’ indefensible demands.

For too long, too many schools have been failing, and too many incompetent teachers have been protected by impenetrable work rules.

Something has to give.

It will if Cuomo keeps his word to break up the monopoly. The consequences could be huge for students and deal a devastating blow to union power.

The upside potential is enormous. Imagine a school system where performance measurements of both students and teachers are honest, and where accountability is real. Those are the stakes that make Albany worth watching.

It must have been a slow news day at The Washington Post: “Supporters say Clinton developing smarter, more relevant campaign for 2016,” a headline declares.

Given the results in 2008, does she have a choice?

Lacking any credible explanation, the dramatic slowdown in cases at the city’s Department of Investigation smells like a political payoff to the unions. Their members benefit most when gumshoes look the other way.

Despite Mayor Bill de Blasio’s promise to demand integrity from city workers, arrests by agency investigators fell 74 percent, compared with a similar period under former Mayor Mike Bloomberg. And referrals for criminal prosecution fell 66 percent, The Post reports.

The agency is headed by Mark Peters, who served as de Blasio’s campaign treasurer. Somebody should tell him the campaign is over and crooks are crooks, even when they are the mayor’s political friends.

But with City Hall defending the agency’s pathetic performance, it’s safe to assume Peters is doing what his boss wants. In that case, maybe the slowdown delivers a message to police unions. Instead of enforcing the law and protecting honest New Yorkers, cops are being invited to join in the rip-off of taxpayers.

All they have to do is kiss the mayor’s ring and — presto! — they’ll be good guys and exempt from the laws.

So it goes in the banana republic formerly known as New York.