Heather Booth doesn’t look like a revolutionary. She sits demurely on a sofa, dressed simply in black, fingering a silver necklace. She speaks softly, selecting her words with care and enunciating cleanly. Dignity. Respect. Community.

But something comes over her when she begins to talk about helping people organize to make their world better. The sweet smile fades. She sits up straighter. Her voice tightens, the words come faster. Power. Together. Act. She strikes a gently curled fist into an open palm. IM-pact.

Booth, 71, is one of the nation’s most influential organizers for progressive causes. Inside almost every liberal drive over the past five decades ― for fair pay, equal justice, abortion rights, workers’ rights, voter rights, civil rights, immigration rights, child care ― you will find Booth. But you may have to look hard.

Because she’s not always at the head of the protest march. More often, she’s at a let’s-get-organized meeting in a suburban church basement or a late-night strategy session in a crumbling neighborhood’s community center. She’s helping people already roused to action figure out practical ways to move their cause forward. And always she’s advancing the credo she learned as a child: that you must not only treat people with dignity and respect, but you must shoulder your own responsibility to help build a society that reflects those values.

Booth is the founder and president of the Midwest Academy, which for over four decades has trained grassroots activists to advance progressive causes across the country. The academy’s goal, according to its website, is both aspirational ― to “give people a sense of their own power to improve society” ― and enormously practical ― to teach a “strategic, rigorous, results-oriented approach to social action.”

To that end, Booth has worked with a range of liberal groups, from USAction, MoveOn, People’s Action, NAACP National Voter Fund, Alliance for Citizenship and the Voter Participation Center, to the National Organization for Women, the National Council of La Raza, the National Committee to Preserve Social Security and Medicare, and the Center for Community Change. (She’s also blogged for HuffPost.)

“Heather is one of the people who makes this all work,” said Sen. Elizabeth Warren (D-Mass.), indicating a sweep of progressive issues ― including the creation of the Consumer Financial Protection Bureau.

Warren, then a Harvard law professor, had a vision of that federal consumer agency in 2007. But she confessed to a colleague that she had no idea how to make it happen, how to harness the political energy needed to push it past the opposition of powerful corporate financial interests.

Her colleague said simply, “Call Heather.”

So it was that, deep in the financial crisis of 2008, with Wall Street giants collapsing, mortgaged homes going under water and banks facing insolvency, throngs of activists appeared to demand real financial reform. They were drawn from labor unions, civil rights organizations, consumer and citizen action groups, and unaffiliated individuals who had never before been politically active but who were furious at the abuse of ordinary Americans.

Booth’s work wasn’t simply a matter of gathering people for protest marches, although those were important. She helped activists devise the tactics to pressure specific legislators. Together they faced off against the monied interests of big business and the political bosses.

And they succeeded. In 2010, President Barack Obama signed the Consumer Financial Protection Bureau into law. Politicians and other notable figures gathered on stage for a gala signing ceremony at the Ronald Reagan Building. Booth was in the back of the auditorium.

But she felt vindicated. In the fight against Goliath, Booth later told Bill Moyers with a disarming smile, “Sometimes David wins.”

Warren said, “I’m in awe.’’

Today, opposition to the actions and conduct of President Donald Trump keeps rolling out in the street and on social media. The ugly firing of FBI Director James Comey has ignited new outrage. But the question is whether all that energy can be harnessed for action beyond protest marches ― or if it will dissipate like the 2011 Occupy Wall Street movement.

That’s where Booth comes in.

The Trump era “is a perilous and inspiring time ― both are true,” she told HuffPost. “The peril can’t be overstated. I do think families will be ripped apart, people will unjustly be imprisoned, jobs will be destroyed. I think lives may be destroyed,” she said. “I fear for unjustified wars. I think the structure of democracy itself will be threatened, from simple protections of people’s health and safety to the ability to live a decent life. So … a time of great peril.”

“But …” She allowed herself a broad smile, offering a glimpse of the spirit that has powered uphill battles all these years. “I am incredibly heartened by the outpouring of people standing up to say, ‘You’re not going to do this. We are going to defend our lives, our families. Our democracy! And we are going to defend each other.’”

“If you stand together and organize,” Booth said, “you can change the world.”

This conviction goes way back. In the early 1950s, the sole African-American child in her first-grade class in Brooklyn, New York ― a boy named Benjamin ― was accused by a white student of having stolen her lunch money. The accuser and her friends crowded around Benjamin, pointing and taunting. Booth pushed her way into the circle, put her arm around Benjamin and just stood with him. (And, of course, the accuser then found her lunch money in her shoe.)

As an adolescent, Booth felt she didn’t fit in. She tried out for the cheerleading squad, but quit when she found out that more talented black girls had been turned away. She volunteered for the school chorus, but apparently had no aptitude for singing. At the Christmas pageant, she was asked to just silently mouth the words.

“I was insecure most of my life,” she said, “and in almost all situations felt I was not good enough, didn’t know enough.”

Even so, one day in her early teens, the would-be activist stood by herself in New York City’s Times Square handing out leaflets urging an end to the death penalty. It wasn’t pleasant. In the late 1950s, Times Square was a vile pit of hucksters, porn shops and addicts. One guy spit on her. Flustered, she kept dropping her leaflets. “I was really frightened,” she said.

The lesson she took from that experience, however, wasn’t that you had to stop protesting, but that you had to stop doing it alone. You had to draw others into the action. Get organized. Together you could achieve results even if you were scared and insecure.

Booth felt that power a few years later in Mississippi, where as a University of Chicago student, she spent the Freedom Summer of 1964 organizing for voter rights. That, too, was frightening and inspiring. “We were standing for something that mattered, that was bigger than ourselves, and if as an individual I didn’t know what I was doing, as a group we did know what we were doing,” she said. “And over time I could see that because of this, we were ending segregation.”

Some years later, as a young mother of toddlers on Chicago’s South Side, Booth gathered a group of working moms to form a neighborhood day care cooperative ― and found the idea blocked by the city’s byzantine licensing codes. So they began organizing other parents across the city, at church and synagogue meetings and other community forums.

“People flocked to us,” Booth recalled in a recent TEDx talk. “People gained confidence, found their voice, spoke about their love for their kids, the child care they needed, their vision for the future.”

They framed the conflict as loving mothers versus uncaring bureaucrats. The press noticed. Then Chicago’s politicians noticed. Within six months, she said the city had agreed to one-stop licensing, a licensing review board of parents and child care providers, and $1 million for new child care centers.

The potency of targeted, strategic organizing is a key idea taught at the Midwest Academy, which Booth started in 1973. She chose the name not for the academy’s location, Chicago, but because it sounded wholesome, a clean break from the strident rhetoric of the student left. “We didn’t want to be mean,” she explained.

Three core ideas guide the 25,000 activists who have trained at the academy: The goal of organizing must be concrete improvement in people’s lives. The organizing must help ordinary people develop their own sense of power. And activists should seek change that is systemic ― not just fixing the water supply in Flint, but giving people in Flint some oversight of the water system.

Among the academy’s teaching materials is a strategic planning chart to help organizers link a specific and achievable goal with available resources (money, allies, media contacts), the names of decision-makers whose support or acquiescence is needed, the tactics required to win over opponents, and the messaging to mobilize others to join in.

“Rather than saying, ‘Oh, this is awful, they’re giving money to the wealthiest and taking away our fundamental services, so let’s do a hands-around-the-Capitol’ ― well, that may be a good thing to do,” Booth said. “But can we do it in a way that builds our organization’s resources, brings in more people, maybe raises funds? And afterwards, let’s look at what worked and what didn’t work. What do we do next?”

As valuable as organizing is, Booth understands that it’s a tool for social progress, not the driving force behind it.

“It doesn’t start with training, although the training helps people be more effective,” she said. “It starts where there is an injustice in the world ― people living in fear that some family member will be deported who’s been here 20 years. And people say, ‘We need to do something about that. Let’s take some action.’”

After a police officer killed black teen Michael Brown, for instance, “there was an outpouring across the country. No one had to be told, ‘I can’t take it anymore.’ Not just ‘I can’t,’ but ‘we can’t.’ So it starts with people’s anger, love, fear, hate, concern and standing up to say, ‘It can’t continue like this.’”

Today, at a time when many feel powerless and despairing, Booth draws inspiration and energy from the protests that have been erupting since Trump’s inauguration. “We are gaining strength,” she observed.

“The size, the numbers, the beauty of the effort, how representative it is of America ― all of America ― the number of places it’s happening. And how beautifully nonviolent, peaceful and intense they are simultaneously.”