When you're young, it's easy to think your career is the most important thing in your life. Working 80-hour weeks, giving up any semblance of a normal social life, and traveling to the four corners of the world at a moment's notice are all part of a day's work for many young professionals. The lifestyle may not be ideal, but the pay can be nice. When you're still trying to pay off debt from student loans and credit card bills you spent your college years running up, that paycheck can seem like the most important thing.

As you get older, your willingness to sacrifice everything for your career may start to wane. Yet as education debt is replaced by mortgage debt and the financial burdens that children bring to your family, your financial need to keep bringing home large paychecks may continue well into middle age. You may also be concerned about the effect that reducing your income will have on your retirement. At least when it comes to Social Security, however, taking a lower-paying job won't necessarily have as large an impact on your retirement benefits as you might think.

Social Security and income
Social Security benefits are based on the amount you earn over the course of your career. In calculating benefit amounts, the Social Security Administration considers the 35 years in which you earned the most money, after your earnings are adjusted for inflation. Therefore, during the first 35 years of your career, anything you make will help to improve your retirement income levels. Typically, professionals start out making far less than they eventually earn after years of experience. As a result, those last few years before you retire are often the ones that contribute the most to higher Social Security benefits.

Yet even if you choose to pursue other, less lucrative lines of work, you may be surprised at how little an impact it has on your retirement benefits. Assume, for instance, that you were born in 1970 and have earned $100,000 per year since you started your first job in 1997. That salary is enough to max out your Social Security contribution. If your salary rises at the rate of inflation for the rest of your career, then the government's trusty Social Security calculator reports that your benefits will be about $2,300 per month in current dollars.

Say, though, that you're already burned out and want to consider taking a less stressful job that doesn't pay as much. If you decide to take a job that pays slightly less -- $75,000 per year -- then you might expect your benefits to fall by roughly 25%. However, the actual impact is closer to 10%, with a monthly benefit of just less than $2,100. Taking a pay cut of 50% still leaves you with a benefit of more than $1,850, and even if you take a job paying $25,000, you'll still end up with $1,560 -- two-thirds of what you'd have been making if you'd stayed in your fast-lane job.

Other retirement resources
Of course, there's more to retirement planning than just Social Security. Earning less means you won't have as much to set aside from your own earnings. You probably won't be able to put as much into an employer-sponsored retirement plan like a 401(k), and it's likely that you'll get smaller contributions from your employer for profit sharing and employer matching programs. On the other hand, with companies like Ford (NYSE:F) and General Motors (NYSE:GM) struggling with underfunded pensions, it may not be too wise to rely on your employer for retirement help anyway.

Financial considerations play a major role in planning for your retirement. Yet if your current job is causing you more stress and anxiety than it's worth, you may need to put financial concerns on the back burner and focus instead on your immediate well-being. If you've worked at high-paying jobs for a number of years, you can feel better knowing that you've already earned a significant part of your Social Security benefits.

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Fool contributor Dan Caplinger has stepped in and out of the fast lane several times during his career. The Fool's disclosure policy follows you everywhere you go.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.