Not saving enough -- or at all
Once you sign up, figuring out the best amount to contribute is the next hurdle. Not surprisingly, most people don't contribute enough.
According to Webb, the average contribution rate is 6 percent. Combined with a typical 50 percent match from the employer, the average employee saves 9 percent of salary annually.
"If the employee started (saving) at age 22 and contributed every year to age 66, that might possibly be enough. But if you add in gaps, late starters or all the rest to it, then the calculations that we have done at the center show that 9 percent is really, really not enough," says Webb.
If 9 percent is not enough, zero is much worse. A recent survey by financial services organization TIAA-CREF found that 80 percent of those asked were not contributing to an IRA and nearly half, 43 percent, could not even identify an IRA correctly.
Reasons abound why investors arrive at retirement with less than an optimal amount. One person may have endured a massive, uninsured health problem; someone else may have experienced a prolonged period of unemployment. Many people simply just do not save enough.
Whatever the reason, those who come up short may find they need to work longer and save harder than someone who started saving in their early 20s.