Early retirement is a goal for many people, but you'll have to figure out how to cover your costs if you're no longer actively working to earn money. This is where retirement investment accounts come in, right? Well, if you're older than 59 and a half, sure. But if you're younger than that, you'll be penalized for withdrawing money from these accounts. Here's what to consider if you're retiring early and intend to rely on your investments to fund your post-work life.