A recent study of 401(k) plan investors with more than $1 million in assets might surprise you — but it shouldn’t. Start early enough and save often enough and you won’t have to make millions to save a million.

Nor does it take tremendous sacrifice.

Fidelity Investments is one of the nation's largest 401(k) trustees. A recent “Fidelity Viewpoint” report looked at 1,100 employees making under $150,000 that accumulated more than $1 million in their Fidelity 401(k) plan. Fidelity studied the transaction history in these accounts from 2000 to 2012 to see how these "401(k) millionaires" accomplished this noteworthy feat.

Note: all "average" data in the report represents the median value — half more, half less.

The average 401(k) millionaire is 59 and has worked 34 years for their current employer. They began saving early and let the power of compounded, tax-deferred growth work on their behalf.

During the 12 years under study, the average 401(k) millionaire deferred 14% of pay — about $13,300 annually, indicating that the average salary was less than $100,000 during these years.

Salary deferrals were large enough to take advantage of the “free” money of the employer match. The average annual company contribution was about 5%, for a total annual contribution of 19% of pay. Stated another way, 28% of the contributions to the average 401(k) millionaire’s account came from his or her employer.

The average 401(k) millionaire had 75% of their 401(k) assets invested in equities. Their portfolios yielded an average annualized return of 4.8% during the 12 years Fidelity studied. After adding employer contributions, the average account balance grew by 8.75% annually.

You may not need to accumulate $1 million in your 401(k) to achieve your retirement goals. However, by mimicking the habits of Fidelity's 401(k) millionaires you'll maximize the potential of your 401(k).

Fund your 401(k) to the maximum extent possible. The average 401(k) millionaire had a 14% salary deferral. The adage of saving 10% of income is obsolete; a relic of a prior time when corporations provided defined benefit pensions. For most employees today, their 401(k) will make up the bulk of their retirement portfolio and be the primary source of retirement income. In a 30- to 40-year working career, a 15% salary deferral and a 3% employer match, if properly managed and allocated, should create an account balance sufficient to produce an annual income equal to a typical defined benefit plan.

The average 401(k) millionaire was a long tenured employee. It's unlikely that today's average employee will work for the same employer for more than three decades. The portability offered by a 401(k) plan makes it a superior option to a traditional defined benefit plan for today's highly mobile workforce. If employees discipline themselves to rollover assets from a former employer's 401(k) to an IRA or to their new 401(k), job changes should have no impact on their retirement nest egg.

The relatively high allocation to stocks among Fidelity's millionaires may or may not be appropriate for you. However, it shows that a significant portion of your 401(k) should be permanently allocated to stocks, regardless of age.

To my way of thinking, your 401(k) isn't a pension — it's an account balance.

You face the daunting task of making that account balance large enough to generate a retirement income that lasts as long as you do. Apart from your loved ones, nobody will care if you succeed or fail. Unlike Fidelity's 401(k) millionaires, many do-it-yourself investors know just enough to get themselves into trouble; making decisions out of impulse that they mistake for insight.

Like it or not, you must acquire or hire the skills necessary to accomplish this difficult task. Then, someday, you just might become a 401(k) millionaire.