Our attitudes toward time shape every part of our lives, and yet few recognize how this subtle fact can sabotage careers or vault them skyward, wreck marriages and make people happy (or not), suggests a new book.

"The Time Paradox: The New Psychology of Time That Will Change Your Life" (Free Press) by Stanford University psychologist Philip Zimbardo and John Boyd, research manager at Google, is not a time-management book. After surveying more than 10,000 adults over the past 30 years, he and Boyd have identified six ways in which people view time. Nobody has only one way of viewing time, but how high or low you rank in each category is linked to your odds of being happy, mentally healthy or successful, he says.

There's one timeless truth about time: It's a major problem for people.

"Not enough free time together" is the top source of stress in marriage, above finances and sex, according to more than 2,000 people who took an unscientific USA Today online survey in July; it also ranked first in a nationally representative, scientific poll 21 years ago commissioned by the paper. Life is busier this year than last, about half said in both polls, and nearly all respondents said they craved more time with friends and family.

But would it be happy time?

"Mismatches" between people who view time differently are common in marriages, Zimbardo says. When future-oriented spouses clash with mates who live mostly for fun in the present, "you hear 'He's irresponsible' and 'She's a slave-driver,' " he says. Trouble can erupt over how to spend money, free time or vacations, and how to raise kids.

FOCUS ON FUTURE

Many ambitious middle-class families are future-focused because they want their children to have a good future.

Ann Adams, 43, an architect in Colorado Springs, Colo., who has two boys, rises at 4 a.m. and goes nonstop till late at night, she says. She takes conference calls in the car as she drives the kids, who are on six different teams, to athletic events. "I threaten them with their lives if they don't stay quiet on work calls while I'm driving," she says.

But she doesn't think cutting back activities is the answer. "My son has to go to batting practice because he needs to make the varsity team because it will help him get into college."

When asked what she does to relax, she just laughs. "There is no time to relax."

Greg Marrow, an optometric physician in McGaheysville, Va., knows what it's like to run on a treadmill with eyes fixed on the horizon. After he and his wife opened their practice seven years ago, they were swamped with patients. Their hours expanded.

Renting out extra suites in an office building had Marrow doing most of the building work, he says.

Three years ago, he turned 40. "All of a sudden, you're 40 years old, and you realize 'The time is now!' Life is just moving way too fast, and I'm not enjoying the present enough. I realized my 'true north' was about my family, but I was making it about everything else in the future."

Marrow and his wife cut their hours and hired another doctor for their practice. "I'm trying to turn it around, I really want to savor the present," he says.

The Marrows may be part of a new wave of well-educated parents who increasingly take their children off fast-track activity schedules to assure a good future, says James Chung, president of Reach Advisors, a marketing research firm.

Whatever your attitude toward time, though, it can be changed, Zimbardo emphasizes. Their book offers exercises to "reset your perspective clock."

Marrow says he's relishing his own midlife shift in time perspective: "Life is not a sprint. It's a marathon."