(CNN)Amir Hekmati always made sure

(CNN)Amir Hekmati always made sure his workout buddies had some fuel in their system before hitting the gym. His close friend Arash Ansari would sometimes skip lunch, but that didn't fly with Hekmati.

"It's very important -- you're a growing boy," Ansari remembers his friend saying.

Hekmati would grab the blender and make his buddy a shake.

"It was just one of his weekly 'Amir things' that I almost looked forward to," Ansari said. "I kind of skipped lunch sometimes just to hear him say that to me."

Hekmati -- a former Marine -- is one of three Americans the U.S. government has acknowledged are being detained in Iran. A fourth, Robert Levinson, was reported missing after a visit to Iran.

With the announcement of a nuclear deal between Iran and world powers, their families and friends hope that the fight to free their loved ones won't be ignored. They include Naghmeh Abedini, whose husband, Saeed Abedini, is a Christian pastor imprisoned in Iran.

"With the announcement of a deal and yet silence as to the fate of Saeed and the other Americans held hostage in Iran, their fate lies now in the hands of Congress," she said in a statement, pleading with Congress to keep the detained Americans in mind as it reviews the deal.

"My children have desperately missed the loving embrace of their father for the last three years of their lives. They have grown up almost half of their lives without their father," she said. "Please help us ensure the remainder of their childhood includes both a mother and a father."

Hekmati's family also released a statement after the nuclear deal was announced.

"Amir is an innocent man who traveled to Iran to visit family, yet there is no denying that his imprisonment has been prolonged pending an outcome in these negotiations," the statement said. "While Amir himself has said that he should not be part of any nuclear deal, his immediate release would demonstrate a strong gesture of good faith to the international community."

Ali Rezaian absorbed news of the nuclear agreement Tuesday with thoughts of his brother, Jason, a Washington Post reporter who remains locked up in Iran.

"Jason is completely innocent of all charges and it is inhumane for him to still be held behind bars after nearly a year," Ali Rezaian said in a statement. "We are hopeful that with the agreement now in place the Iranian courts will conclude this process swiftly and affirm Jason's innocence so we can bring him home and make our family whole again."

Christine Levinson implored the United States and Iran to keep working together -- "with the same sense of urgency" they applied to reaching a nuclear deal -- to free her husband, Bob, a former FBI agent who vanished in Iran in 2007.

"Bob has been held against his will for eight years," she said. "This nightmare must end."

Their son, David, said the family desperately wants his father home.

"What we believe is that this deal is not the end of discussions between the Iranian government and the United States government, but merely the beginning," he told CNN's Wolf Blitzer Tuesday.

A month of mercy
Amir Hekmati has been detained since 2011 on charges that he was spying for the United States -- charges he flatly denies.

He has lost nearly 30 pounds and has trouble breathing, according to his brother-in-law. He might have a lung infection, and his family worries that if Hekmati is not treated, he could contract tuberculosis.

"I can't understand how four years have gone by and we are just now getting the most basic attention on his case," Ansari said. "I don't know -- I can't understand -- how Amir has not been a priority. He should've been released, you know, six months into his detainment, at most. And now we're approaching four years."

Hekmati's family hopes that having Iranian and American diplomats already in rooms together, in timing underscored by the magnanimous spirit that embodies the Islamic holy month of Ramadan, will be enough to secure Amir's release.

Hekmati's sister, Sarah, and her husband, Ramy Kurdi, traveled to Vienna, where the nuclear negotiations were being held, to make sure Amir Hekmati's case wasn't forgotten.

"This month is Ramadan, as Ramy mentioned. A month that the supreme leader could show Amir mercy," she said. "I have come all this way because our family needs answers."

White House Press Secretary Josh Earnest acknowledged this month that U.S. diplomats have brought up the cases of Americans being detained in Iran on the sidelines of the nuclear negotiations.

"This is something that we continue push hard on irrespective of the nuclear deal," President Barack Obama said last month at a news conference. "We spend a lot of time pushing on it and we will continue to do so."


Obama: 'Deeply concerned' about Americans held in Iran 01:05
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U.S. Deputy Secretary of State Tony Blinken said in June that Washington has insisted that Iran release Hekmati, Rezaian and Abedini. His boss, Secretary of State John Kerry, echoed that sentiment Tuesday morning when the deal was announced.

"We continue to call on Iran to immediately released the detained U.S. citizens," Kerry said. "These Americans have remained in our thoughts throughout this negotiation, and we will continue to work for their safe and swift return."

The Obama administration contends that the negotiations on behalf of Americans being held in Iran and the status of that country's nuclear program are separate issues.

The issue was not technically on the negotiating table, but the agreement on the nuclear deal could help improve the climate of any potential future negotiations, says Vali Nasr, dean of the School of Advanced International Studies at Johns Hopkins University.

"Clearly in a frozen relationship, either they're kept as pawns or largely they become essentially a facet of the confrontation," Nasr says. "If the relationship is not confrontational, or it's more stable, then it is more likely that that issue can be resolved."

Some say the detained Americans and nuclear negotiations are inextricably linked.

"The scale of Iran's current hostage-taking -- not only (Jason) Rezaian but also Iranian-Americans Saeed Abedini and Amir Hekmati -- may pale in comparison with Iranian behavior of decades past," author Michael Rubin wrote in an opinion piece for CNN in March. "But the use of hostages to extract concessions or dampen the enthusiasm surrounding reconciliation is part of a consistent pattern."


2013: Family pleads with Iran to release son 04:33
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Hekmati's friends and family worry that if he's not freed soon, he may miss his last chance to see his dying father. Ali Hekmati is suffering from brain cancer and has had two strokes since his diagnosis, according to Kurdi, Amir Hekmati's brother-in-law. Ansari says Ali Hekmati gets worse every day.

"I want my dad to hold his son again. I want my mom's heart to stop breaking," Sarah Hekmati said, fighting back tears. "I want the hole that we all feel by his absence to be filled.