Secret #3: Use reminders and checklists

Human beings are prone to distraction by immediate events -- helpful in the days when an angry wildebeest might interrupt your dinner, but not so much when you're planning for retirement. "Reminders are one of the simplest, lowest-cost ways to cut through distractions and stay focused on your goal," says Yale's Karlan.

He and other researchers working with banks in Peru, Bolivia, and the Philippines looked at the impact of sending account holders reminders to save by text message or postcard. The savers who got those messages put away as much as 16% more.

Checklists are another effective tool to help you stay on task. As Harvard surgeon Atul Gawande pointed out in his 2009 book, The Checklist Manifesto, the simple act of going through one of these lists can help you avoid missing a vital step.

When surgeons and airline pilots began using them, hospital infection rates and pilot error declined. No wonder so many financial advisers rely on checklists for clients nearing retirement.

Put these findings into action:

Arrange automatic prompts. It's easy: Just set e-mail alerts in your digital calendar or via a personal finance website such as Mint.com. The most effective, says Karlan, are as specific as possible ("put $1,000 in my Roth IRA on Dec. 1," not "save more for retirement"). Arrange for them to hit your in-box at tax time, at bonus time, and after your year-end statements arrive (to prompt you to rebalance).

Put a reminder where you'll see it every day. Remember that Northwestern study showing that thinking about a grandparent can help you save? Study subjects wore wristbands with the acronym WWGD (What Would Grandma/Grandpa Do?) written on them. Hokey, sure -- but effective. Placing a reminder of your goal where you'll see it day in and day out (a photo of your dream retirement house by your bed, for example) could have a similar effect.