Working in conflict zones for years does not make it any less frightening when armed militiamen storm the hospital you run, says Colette Gadenne of medical charity Medecins Sans Frontieres (MSF).
This happened three times in three weeks from May to June in Central African Republic, where Gadenne is head of the mission.
In one case, the fighters fired 21 rounds before leaving.
Central African Republic is a particularly bad case, but aid workers worldwide are facing an increase in raids, killings and kidnappings as fighters flout the international laws meant to protect humanitarians, aid groups said.
This has changed the way agencies operate, forcing staff at all levels to grow accustomed to a constant level of danger and hone skills such as negotiating with armed groups, experts said.
"It is scary. Even if you have experience, even when you know you have a good network, it remains scary," Gadenne told the Thomson Reuters Foundation by telephone from Central African Republic's capital, Bangui.
Nearly 140 aid workers were killed last year worldwide, a 23 percent rise over 2016, according to data released this week by independent research group Humanitarian Outcomes.
South Sudan was the most dangerous country for the third year in a row, while Central African Republic rose to fourth on the list, after Syria and Afghanistan, following a three-fold rise in attacks.
The dangers limit the areas aid workers can enter, leaving more and more people without help, said Sofie Garde Thomle, head of the United Nations' Office for the Coordination of Humanitarian Affairs (OCHA) in West and Central Africa.
"Most importantly, the lack of access means we see a much higher loss of lives," she told the Thomson Reuters Foundation.
"If you look back 10 or 20 years ago, it was completely different," she added, speaking ahead of World Humanitarian Day on Sunday, a tribute to aid workers who risk their lives.
Today there is less respect for the rules of war, the international laws that protect people in conflict zones who are not fighting, Thomle said.
"We could expect to be spared because our medical actions are extremely clear," said Gadenne of MSF.
MSF staff in Central African Republic are in constant contact with various militias to negotiate access and give help to those who need it, she said. But the staff fell victim to 40 attacks in the country last year.
"We do a lot of discussion with armed groups... and it didn't work," Gadenne said.
Spending more on security
Justin Byworth, humanitarian director for global charity World Vision, was working in South Sudan in May when nine colleagues were kidnapped and held for five days. OCHA was able to negotiate their release.
"I was very conscious every day of what they were going through," Byworth said. "You're scenario-planning very rapidly."
In recent years the charity has spent more money on security and staff care and focused on providing local psychosocial support, he told the Thomson Reuters Foundation.
Sometimes staff hail from conflict zones themselves or have had multiple postings in dangerous places, and each incident can trigger memories of past traumatic events, he said.
But in many cases aid workers are not targeted specifically - they are simply caught in growing violence against civilians, Byworth said.
"Ultimately the challenges pale in comparison to the risks the population faces every day," he said. "It's not surprising if we get a taste of that as well."