(CNN) -- This year's graduating seniors may face higher risk for job burnout than their parents' generation, say business and career experts.
Merav Fine, left, and Ruth Igielnik, may face tougher challenges to balance their careers and personal lives.
One of those grads, 22-year-old Ruth Igielnik, kicked off her career at a Washington political polling firm just weeks after donning her cap and gown at the University of Maryland.
"I'm going to be available as much as they need me," she says, acknowledging the long hours she'll be working ahead of November elections.
Igielnik should be familiar with stretching her boundaries. She admits classes were an "afterthought" during the past year because she toiled from two to five hours every school night as student overseer of 300 campus groups.
"I'm certainly willing to stretch the bounds of my daily schedule," she says.
But new grads in entry-level career jobs should resist early urges to sacrifice personal time in exchange for a faster climb to the top, warns career consultant Alexandra Levit. See more tips on how entry-level grads can protect personal time »
"You have to go out of your way to protect your time, but you have to go about it more subtly," she says. "If you sacrifice too much of your personal life at the start, you risk having a stressful, unbalanced life that's permanent."
Levit specializes in so-called millennials, the generation born from about 1980 to 1995. She agrees with other experts who fear millennials are at risk for early job burnout.
In the next two to four years, retiring manager baby boomers will trigger a wave of new openings for high-responsibility jobs, says Levit. A lot of those jobs will be filled by less-experienced workers -- many of them millennials.
"Their sense of entitlement and their over-ambition are going to create a lot of stress for them," Levit says. "They're going to be given the responsibility they crave -- because there's no one else to take it."
These young managers will have trouble getting their arms around their job responsibilities, says Levit. Their drive to succeed -- typical among millennials -- will be exacerbated by a world where technology makes work possible virtually anywhere, 24-7.
Experts say this generational shift also will challenge graduates who are not so ambitious and career-driven. It will force many of them who put free time above their careers to take on more work.
Keys to protecting work-life balance include defining what's important outside of work -- such as family, friends, volunteering, hobbies -- and committing to it, according to Levit.
Bosses and employees each should have a clear understanding of what's expected of employees, and how far beyond the call of duty workers are expected to go, she says.
Although millennials often value work-life balance, they also tend to limit their loyalty to employers, says author and consultant Lindsey Pollak. "They don't feel that the work force is going to be loyal to them. So why should they feel loyal to the work force?"
"I'm realistic," says Igielnik. "I realize that these days the 40-year career that our parents experienced doesn't really exist anymore, and it's pretty common to jump around. So I wouldn't be shocked if I didn't spend my entire life at one company."
A friend of Igielnik's, Merav Fine, is taking a few weeks off before joining the work force as a legal assistant at a small Washington-area law firm. Fine jokes that -- after a heavy class schedule and an intense internship for a Washington congressman -- school has left her burned out before she's even begun her career.
The New York City native worries that her career might steal time she should spend with friends and family.
Professional services firm Ernst & Young predicts that, by 2010, millennials will equal 60 percent of its workforce. The company plans to hire 3,300 new full-timers this year. Rival firm Deloitte plans to hire about 4,000 new full-timers this year. See Fortune list of "100 best companies to work for"
"There is a pending talent shortage upon us," says Deloitte's Diane Borhani, who's unapologetic about the hard work and long hours put in by the corporation's workforce.
Millennials aren't afraid of working hard, she says. "They just want to have freedom to do other things."
However, compared with previous generations, many millennials are "backlashing against the idea that your work is your life," says Alexandra Robbins, author of "The Overachievers: The Secret Lives of Driven Kids." They're "intent on finding jobs that are meaningful both personally and to the community and the environment."
Deloitte is offering its new hires a chance to make a difference, with programs like Impact Day, when employees devote a day to local community improvement projects. Ernst & Young also promotes environmental issues among its workers.
Both firms have made efforts to introduce flexibility into their work culture. Deloitte's Mass Career Customization program offers workers options to accelerate or slow their careers to suit their personal needs. Ernst & Young offers Summer Hours, where some teams may choose to work more hours earlier in the week in exchange for half-days on Fridays.
"The things that this generation is asking for -- flexibility, balance, opportunities -- are all things that previous generations wanted," says Dan Black, top campus recruiter at Ernst & Young. "But they feel much more emboldened to ask for these things. They know they're going to be a bigger part of the work force."