We all want to get more done in less time. There are tools galore that are supposed to help us be more productive, from sleek, cloud-based to-do list apps to complicated, low-tech journaling methods.

Do you really need any of it?

No, says productivity-obsessed CEO Marc Zao-Sanders.

The co-founder of education platform Filtered.com says you really don't even need a to-do list. By nature, to-do lists set us up to fail for a multitude of reasons. We live for the thrill of crossing off easy and unimportant to-do list items, only to let the hard, really important items languish.

Since he ditched his to-do list and adopted a proven time-management technique, Zao-Sanders claims, he's doubled his productivity. All you need is a calendar.

Put it on the calendar

It's called time-boxing, and the term is borrowed from agile project management. It simply means setting a specific period of time to accomplishing a certain task. Put it on your calendar. Stick to it. Your calendar then becomes your to-do list.

Zao-Sanders waxed poetic about all the benefits of time-boxing for Harvard Business Review. His company also ranked 100 popular productivity hacks, and they deemed time-boxing as the number one most useful and easiest to execute.

The standard workday typically involves meeting with other members of your team for planned blocks of time, ideally with a purpose and outcome in mind. Why not schedule meetings with yourself to accomplish the same goal?

It makes your to-do list visual

On a standard to-do list, everything has equal visual priority. Naturally, some things will take longer than others. We know this, but the to-do list format doesn't provide a quick read. It's just a list.

With time-boxing, you estimate how long you think things will take and plot those chunks of time out on your calendar:

  • Plow through emails: 30 minutes. (Mark Cuban is an expert at this)
  • Create PowerPoint deck for Friday's presentation: three hours
  • Submit expenses from last work trip: 20 minutes

If you're new to time-boxing, you might not get the estimates exactly right at first. Adjust as you go. You'll learn to be realistic about what you can accomplish in a given period of time. Remember that you're only human, and you can't be 100 percent productive all the time. You might lose time to chatting with colleagues, eating food, or going for a 10-minute walk to clear your head. You don't necessarily need to schedule all those things in your calendar, but leave some wiggle room so you have a little flexibility.

Your future self will find time-boxing useful, and not only because you're being more productive. Zao-Sanders points out that your calendar can become a catalog of things you did and accomplished. When performance review time comes, you'll be able to share in more detail what you accomplished.

It keeps you honest

It's human nature that we don't really want to do the hard, non-urgent stuff. That's why it's so hard to get it done. But, by putting it on your calendar, you push yourself to actually do it.

This is one reason why fitness gurus recommend that you block out times to exercise on your calendar. It's just like time-boxing. If you think you'll make it to the gym eventually, it probably won't happen. But if you schedule it -- and stick to it -- you're more likely to follow through. ​