History has shown us that bull markets last longer and outperform bear markets over time, and that the S&P 500 has generated about a 10% annual total return over the long haul, so keep that in mind as you build your nest egg. Starting early, without question, is the most important factor in supercharging your retirement savings. The more time you are invested in the market, the more time you have for your investments to compound, or gain earnings on top of earnings.