But few exemplify that more than Greg Masi. He may be retired as a Philadelphia police officer but he's continuing his service -- this time as a so-called "Second Alarmer."
And he's still very much answering the call to help.
Chief Gregory Masi served with the Philadelphia Police Department for 40 years. He retired in 2017 after a fulfilling career as a police sergeant.
"Once I retired, I always believed that you should never retire from but retire to. You have to do something with your life to get what I call 'a sense of purpose,'" said Masi.
He says he gets that sense of purpose by volunteering for the Philadelphia Second Alarmers Association. It's a nonprofit that works to give first responders rest and rehab during long emergency services, 365 days a year.
"Our job is to go in there and provide the nutritional side food, fluids, equipment, and make their job a little bit easier while performing this emergency task," said Masi.
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What they do for first responders ranges from providing water, coffee, and cool towels to setting up mobile kitchens, tents for shade, and medic units with rehab equipment.
For 60 years, they've also been serving a green electrolyte-filled drink meant to aid in hydration. They call it "bug juice."
"When it gets really hot, if we don't hydrate these firefighters and police officers what happens? They will suffer heat exhaustion and more serious issues such as a heat stroke," he says. "Almost 50% of firefighter fatalities are caused by not proper hydration."
Philadelphia Second Alarmers date all the way back to 1921. So for almost 100 years, this organization has been living by the motto, "We all have your back."
"It's a real life rewarding feeling when you serve a responder. You can see it on their face how much they really appreciate what you just did for them," Masi says.
Tell us about the person or organization that is doing great things in your community.