So who volunteers the most? It turns out that women volunteer more than men, and 33-44-year-olds were most likely to volunteer their time.
But you're never too old to volunteer, just ask a World War II veteran working a different battle. He helps cancer patients fight for recovery.
88-year-old Bob Gerlach has been volunteering at the Banner MD Anderson Cancer Center's information desk in Gilbert since it opened nearly four years ago.
Not only is he a cancer survivor, he's a veteran and knows all about battles.
"I had two aircraft carriers I served on; the U.S.S. Antietam and the U.S.S. Mission Bay, I served in the Pacific Theater until 1945," said Bob Gerlach.
But this time he is helping other people fight their battles.
"Bob comes and fights an entirely different kind of battle, he fights with our cancer patients, and helps them and directs them through our cancer center," said volunteer coordinator Angie Wiebler.
Wiebler says that many veterans like Bob volunteer.
"We really, truly believe they are everyday heroes," she said.
And during National volunteer week, she says it is only right to highlight all they do, for no paycheck.
"They are just truly giving loyal, compassionate people that give up their time just because they can, just because they want to, said Wiebler.
Gerlach says it's a rewarding job.
"Make them feel at, I mean, not at home, that's a bad word to use in a hospital, but make them feel comfortable with the environment," said Gerlach.
Gerlach says volunteering is in his blood, and the patients are more like family.
The cancer center is always looking for more volunteers if you're interested visit: https://www.bannerhealth.com/Locations/Arizona/Banner+MD+Anderson+Cancer+Center/Ways+to+Give/Be+a+Volunteer/About+Our+Volunteers.htm