Here’s the ugly truth: The highest priority for members of Congress is not to legislate. It’s to stay in Congress. Every vote — especially every bipartisan vote — risks marring incumbents’ records of ideological purity and opens the door to primary challengers from the far right or far left. The main thing that overcomes such stagnation is sustained political pressure put on members of Congress by activists who mobilize public opinion for change.

Activists are why we have the Civil Rights Acts and the Voting Rights Act. Seatbelt laws that swept the country. The Religious Freedom Restoration Act of 1993. The assault weapons ban in 1994. Campaign finance reform in 2002.

In other words, motivated members of the public are largely responsible for some of our country’s most significant legislation. But in recent years, activists seem to have become more impulsive and impatient, demanding swift action on big problems without the kind of compromise and incremental work that creates real and lasting change. Rose Garden signing ceremonies feel good in the moment, but too often their thrills fade fast. Big, swift executive actions — issued by presidents without going through Congress — have frequently blown up in our faces.

So I have a plea for activists on the left and on the right, many of whom I don’t agree with: You have enormous power, more than you may realize. If you master the art of impulse control and play a longer game to put pressure on Congress to get solidly crafted, consensus legislation, you may have a better chance at achieving lasting change on issues like gun control, religious liberty and immigration. And without it, well, look around.

Take gun control. It’s been nearly seven years since Stephen Paddock fatally shot 60 people and injured hundreds more at an outdoor music festival in Las Vegas. It was the deadliest mass shooting in modern American history, and it was enabled in part by bump stocks, accessories that let semiautomatic rifles spray bullets much faster. In 11 minutes, Mr. Paddock fired over 1,000 bullets.

In the wake of the shooting, 82 percent of surveyed Americans said they supported a ban on bump stocks. Activists put pressure on Congress to amend the 1934 National Firearms Act to add bump stocks to the definition of what makes a weapon an illegal machine gun. Congress responded, and within a month, the Senate and the House had introduced bills to ban bump stocks.