To live an abundant retirement lifestyle, you can no longer rely solely on a company pension plan or Social Security. Instead, you will have to depend on how skillfully you plan and invest, and whether you make good use of tax-advantaged savings plans such as 401(k)s and IRAs.

First, estimate how much you will need. One rule of thumb is that you’ll need 80% of your annual pre-retirement income to live comfortably. That might be enough if you’ve paid off your mortgage and are in excellent health when you kiss the office goodbye.

But keep this in mind, when you were working you had a two day weekend. When you’re retired, you’ll have a seven day weekend and will most likely spend more money. So if you plan to build your dream house, trot around the globe, or get that Ph.D. in philosophy you’ve always wanted, you may need 100% of your income or more.

Remember, too, that your health care expenses are likely to go up in retirement, if only because you’ll be paying more for insurance, especially if you retired prior to being eligible for Medicare. Some employees who retire before 62 don’t realize how much their employers contribute to health care, which has led some to consider retiring after 65.

Second, figure out how you’ll meet those expenses. There are three main sources of retirement income: Social Security, pensions/ annuities, and your savings. Start by determining your estimated Social Security benefits. (You can order one online or use an online calculator to make estimates based on expected earnings.)

Next, add in any annual payouts you expect from an annuity or company pension.

If it’s not enough, it’s time to think about where that money will come from. Count on needing at least $15 to $20 in investment savings to cover each dollar of that shortfall. If your projected retirement expenses exceed Social Security and pensions by, say, $20,000 a year, that means you’ll need a nest egg of $300,000 to $400,000 to bridge the gap.

Take some time to plan out your numbers so you’re prepared heading into what should be some of the best years of your life.