We've already mentioned why not investing in a 401(k)—especially if your employer offers a company match—isn't a very bright idea, but according to new data compiled by Fidelity Investments, 401(k) balances are about 62% higher now than they were this time in 2009, which means that if you've been holding out because you're worried about the economy—or stopped because you lost money in the last recession, now is a good time to jump back in. More »