You should contribute as much as you can afford to put away for retirement, because every extra dollar you save will have an enormous impact over the long term. Say you are 30 years old and contribute $100 biweekly into your account. At age 60, if you earned 8% on your investment, you would have $306,620.
Annuities that do allow for withdrawals are those aimed at providing some growth in value over time. These types would include variable annuities, fixed index annuities, and deferred fixed annuities. These growth-oriented annuities are designed for long-term financial goals.