Once it's time to go home from a hard day at the office, more and more TV viewers are tuning into shows about much more difficult jobs.

What began with shows like "The Deadliest Job in the World" became a whole genre of tough-guy jobs, from the Alaskan king crab catchers of "Deadliest Catch" to the "Ice Road Truckers." Mike Rowe would find the worst working conditions in Discovery's "Dirty Jobs." And various other jobs would get the showcase — lumberjacks in "Ax Men," oil drillers in "Black Gold."

Last week, NBC premiered "America's Toughest Jobs," a series that blends many of these shows and makes them a reality competition for newcomers who have never tried such feats.

Thom Beers, who nearly single-handedly created the genre with "Deadliest Catch," and extended it with "Ice Road Truckers," "Black Gold" and "Ax Men," said the NBC show, his first on a broadcast network, fulfills the wishes of people who have sent him mail over the years.

"Every time I would do a new series, and I would always get these letters from people saying, 'My boyfriend wants to be a crab fisherman, and he thinks he can do that job,' or 'My girlfriend can be a truck driver,' " Beers told reporters last month.

"So I thought it would be really cool to give ordinary men and women from all walks of life, from all parts of the country, the opportunity to actually go in as a first-time employee, a first day, a greenhorn, and try these jobs out."

Most of the 13 who stepped forward for the competition — including a math teacher, carpenter, researcher and software vice president — were "people that basically spent their lives or their careers working in cubicles, people that basically were looking for a new opportunity, a new change in life," Beers says.

Some were testing themselves, others sought adventure, still others were angling for the prize money — the combined salaries for all the jobs they were doing, totaling about $250,000.

And the economic picture didn't hurt, Beers says, "in these times where people don't necessarily know if their job's going to be there tomorrow."

Besides that, he adds: "A lot of people don't necessarily like their jobs they have now, but they got bills to pay. So they said, you know what? Why don't we go out and revisit those kinds of jobs that actually made America great, those great working class hero, blue-collar jobs.

"That's what these are: Oil, driving trucks, fishermen. This is the backbone of America. This is what made our country great. It was great to get them out of that cubicle, that conceptual life that we're in, and get out there and get some real raw experience in a place with high stakes and high rewards."

There seems to be no end to these types of shows. National Geographic Channel will air another show, "World's Toughest Fixes," on Sept. 28, in which troubleshooter Seth Riley fixes huge electric turbines and installs 360-ton generators for various customers.

On Sept. 25, "Project Xtreme" begins on the DIY network, featuring contractor Jason Cameron looking at New York's most extreme job sites, from an HD screen in Times Square to changing bulbs atop the Empire State Building.

NBC will buy another show from Beers, "Shark Taggers," for next summer. (It and "Toughest Jobs" are co-produced by Gail Berman and Lloyd Braun, who were entertainment division heads for Fox and ABC networks respectively).

Why so many extreme job shows?

"I think it taps into a desire to return to a certain frontier spirit as you watch these shows," says Charles Nordlander, History Channel's vice president for programming and development and executive producer of "Sandhogs" about crews that dig tunnels for water mains and subways under New York City, starting Sept. 7.