I can type nearly 80 words per minute, but I can't write that fast. After nearly 16 years of forced piano lessons, my fingers are quick. It's my brain that's holding me back--the creative, idea-making part of writing. I capture a little burst of words on the page and then think. Another little burst follows, but then I have to go back and fix something else. Then, I wait. Ten minutes tick by and, on a good day, I'll have 400 words on the page. I've timed it again and again.

I know this. I have the data. Yet I still assign myself more writing each day than I can feasibly get done--effectively setting myself up to feel unproductive and unaccomplished at the end of the day.

I've been on this personal productivity mission to write as fast as I type for a while. The mission drives me to consume productivity hacks like they're popcorn. Every listicle, every roundup of the "best" tips, is fuel for the fire.

So when a Freakonomics podcast popped up the other day claiming, "Here's Why All Your Projects Are Always Late -- and What to Do About It", I stopped writing (obviously) to listen. In it, several experts discussed the concept of a planning fallacy. It's a fancy term for something we all apparently do: When planning, we are overly optimistic about how much time it takes to complete any given task. It's a problem for working moms trying to plow through a to do list, like me. It's a problem for innovators trying to launch their products. And, it was a problem for engineering teams trying to break the sound barrier.

It wouldn't be such a big deal if we missed the mark on one-off tasks. For instance, I planned 20 minutes for my "quick" trip to the grocery store, but it took 35 minutes. 15 minutes late in the scheme of life isn't a problem.

The cumulative effect of optimistically estimating every task on your list, however, is a problem. Routinely having to carry over unfinished tasks from one day to the next is a drag. We internalize this as a failure not just to work efficiently, but as a deeper personal failure to get things done, move forward, or be successful.

The alternative is to get better--which means more realistic--about the time it takes to accomplish the tasks on our list. Give up on the fantasy of writing 80 words a minute and just accept that it takes longer than you'd like. We also need to get real about how much time we have. I might technically have a 9-hour workday while my kids are at school and daycare, but it's really much less than that when I subtract out the time I spend responding to email and dealing with the dozens of other distractions and small daily tasks.

To get more realistic, we need data.

At work, timesheets are a good starting point. Capturing information during a project close-out (as if there is a such thing) is a good way to keep a running record of how much time you actually spend on any given task. If your team doesn't have any data on past projects, it'd be worthwhile to take an hour or two to create some based on everyone's collective memory while it's still relatively fresh. This can be done in a brainstorming meeting while someone types into a spreadsheet. You won't have to break the tasks down into minutiae; just pick the major 3 or 4 tasks and plug in the hours it took to go from start to finish.

At home, you can take notes for a couple of days on how long it takes to get everyone up, fed, and out the door. Every parent of a toddler knows that the time it takes to pull a shirt over a 3-year-old's head is significantly less than the actual time required to get them dressed. But, this isn't just about kid management. There are all kinds of life tasks that can be timed and documented over the course of a few days or a weekend.

Once you have the data, review it. There may be a couple of things that scream for greater efficiency. If you can outsource them or make them more efficient, do that. For the rest of the stuff, you have to acknowledge the time required and then practice using that data when you plan your day. Yes, your to do list won't be as impressively long. Some things are going to have to fall off the list or wait for tomorrow. However, overcoming the planning fallacy will have you more impressed with yourself and your ability to get things done--as planned--for once.