"You have to coach them and tell them this is your job, this is not the street.”

National fast-food chains are increasingly relying on senior citizens to do jobs that were once typically filled by teenagers.

Big food chains are on the lookout for workers above the age of 50 to take shifts as dish washers, cooks and cashiers. Trying to lure their new target demographic, eateries like McDonald's and Bob Evans have started recruiting at churches and senior centers, and buying ads on websites of advocacy groups for seniors, Bloomberg ​reported Monday.

According to Bloomberg, the chains are finding that senior citizens posses valuable "soft skills -- a friendly demeanor, punctuality -- that their younger cohorts sometimes lack."

This is also the result of a precipitous decline in teenagers looking for jobs in the fast food industry. In May, The New York Times ​reported that while the industry has nearly doubled since 2010, neither the demand of consumers nor the workforce have kept up. 

Even as the job market nears ​record-breaking tightness, the rate of participation in the fast-food industry of teenagers between 16 and 19 has ​dropped from 45 percent in 2000 to 30 percent today.

But another change has been taking place in the past decade: More senior citizens have started looking for jobs -- some to ease the drone of retirement, others to supplement a meager pension.

“It’s fun for a while, not getting up, not having to punch a clock, not having to get out of bed and grind every day. But after working all your life, sitting around got old. There’s only so many trips to Walmart you can take,Stevenson Williams, a 63-year-old retired construction worker, told Bloomberg about his post-career life.

Today, he works at a chicken joint in North Carolina, where he started as a cleaner and now manages a staff of 13 workers. Some weeks he works over 70 hours, according to Bloomberg. 

"I enjoy the atmosphere, I enjoy the people,” he said.

Williams also instructs the younger members of his team on outgrowing generational impudence. 

“A lot of times with the younger kids now, they can be very disrespectful,” he told Bloomberg. “So you have to coach them and tell them this is your job, this is not the street.”

The US Bureau of Statistics projects that this trend will continue. The participation of workers aged 65-74 in fast food chains is expected grow 4.5 percent by 2024 (over a decade), while the participation of workers aged 16 to 24 is expected to go down by 1.4 percent.

More broadly:  A sharp decline in workforce participation has also been marked among Millennial (aged 25-35) men, ​according to Bloomberg. Since 2007 general employment among Millennial men has dropped by 5 percent, even as employment among Millennial women and senior citizens kept growing. 

This is assumed to be the impact of the 2008 financial downturn which shook the global market just as many Millennials were leaving high school and college and beginning to enter the workforce. The struggle to obtain a job and start saving money in the years immediately after the collapse has stunted the professional lives of many Millennials.