As he pushes a cart full of tomatoes and cucumbers in the market at Bint Jbeil in southern Lebanon, nothing marks out Mahmud as an experienced Hezbollah fighter.
The stocky vegetable vendor in his fifties, who sports a red beard, fought Israel here in 2006, but that battle is now old news.
He has just come back from another front: in Syria, where he fought for 25 days against the rebels who have sought to overthrow President Bashar al-Assad for the past three years.
Since the Shia movement's chief Hassan Nasrallah gave the order more than a year ago, thousands of Hezbollah fighters have fought in Syria, playing a decisive role in key victories for the regime.
Street vendors, farmers, restaurant owners, medical professionals and students have all joined what they call an "existential battle" against "takfiris" -- Sunni extremists.
"When the party called on me to go, I responded. I left my job and I went to stop the takfiris from entering Lebanon," says Mahmud.
"I fought in several regions and took fighters from the region and elsewhere prisoner," he adds.
"Our cause is just. They are mercenaries from Chechnya, Yemen and Libya who want to overthrow Bashar al-Assad, who supported us enormously during the 2006 war against Israel," Mahmud insists.
"It's our duty to help him."
Hezbollah has a powerful presence at many levels of society in Lebanon, with representatives in parliament and strong social service networks.
It is backed by Iran, which has long supplied it with weapons through Syria.
But the group presents its role as protecting Syria from Sunni-dominated rebels who they say want to overthrow the regime because they hate Alawites, including Assad, whose faith is an offshoot of Shia Islam.
The divide between Sunni and Shia Islam goes back some 1,400 years over a disagreement on the Prophet Mohammed's successor.
In another southern Lebanese village, Fatima has not let the death of her husband in the June 2013 battle for Syria's Qusayr stop her from encouraging her son to join the fight.
"I've send Khodr, with dozens of other young men, to do one month of training in Lebanon," she says.
"He must learn to handle weapons so that he can become a fighter like his father."
Next to her, Khodr sorts tobacco seedlings for planting. His beard is just coming in and his eyes are sad.
He wears a picture of his father around his neck and has a pin on his T-shirt bearing Nasrallah's picture and his phrase "Victory awaits us".
His older brother Wissam, 25, came back from Syria a week earlier.
"We obey Sayyed Hassan (Nasrallah) when he invites us to fight. My father died a martyr and we must follow his path," he says.
There are no official figures on how many Hezbollah fighters have been killed in Syria, but several analyses put the toll at around 300.
"Should we let them come and kill us like sheep, like they have done to the Shias in Iraq and Syria? No, we will defeat them as we defeated Israel," Wissam adds.
When they first began fighting in Syria, Hezbollah members refused to discuss their involvement, but now they talk about it with pride, while declining to offer details of their numbers or operations.
At a school in southern Lebanon, Hezbollah posters advertise scouting sessions, but the accompanying photos of young men in military uniforms suggest the training is more combat-based.
In some places, there are voices of dissent against the group's involvement in the conflict next door.
"They sent my son to his death without my approval. Who told them that I wanted my son to die in Syria?" one man asks, declining to be named for fear of incurring Hezbollah's wrath.
But that sentiment is rare among the party's constituents, who also know Hezbollah will support them if their loved ones are killed.
"My family's future is safe if I die. They'll take care of the schooling for my nine-year-old son and look after his health," says Osama, a 38-year-old party member in the city of Tyre.
In Baalbek, a Hezbollah stronghold in eastern Lebanon, 22-year-old Hussein is heading to Iran to undergo a commander training course.
The psychology student's parents are both party members and he has already fought in Syria's northern province of Aleppo.
"I'm very excited about going to Iran to become a battalion chief. It's a promotion," he says, under his mother's watchful eye.