The four percent rule states that you could withdraw four percent of your principal balance every year and live on this indefinitely. That means you need to save 25 times your annual expenses to become financially independent.

The four percent rule is not perfect. There is no risk-free investment that yields that much today. Sudden inflation could also cause a problem.

How long it will take you to amass 25 times your income is based on the percentage of your income you save.

When you save 20 percent of your income, assuming a five percent average annual return, you'll hit 25 times your yearly income in just over 40 years.

You can take advantage of the tax-sheltered retirement accounts like 401(k)s and IRAs.

• If you qualify for a Roth IRA, use it. The Roth IRA will come back to you tax-free when you're older.
• If you contribute to a 401(k) account, at least 5 percent will be matched from your employer. This means you'll only need to save 15 percent of your paycheck. The money you put into a 401(k) will be deducted from your paycheck before taxes.

If you cant save 20 percent, you are not a failure. While everyone should aim for 20 percent, not everyone will hit the target on their first try.

Start small. Start with 1 percent. Slowly increase. Aim for higher, but if it leaves you stressed, scale back. However, keep the 20 percent goal in mind. When you get a raise, increase your saving rate.

If you can't save a good chunk of your paycheck every month, investing once now can help you start saving in the long run.

A favorite investing platform is Betterment, where your money will be automatically invested in index funds. Betterment's fee is a straightforward 0.25 percent of your total portfolio.