Google's '20% rule' shows exactly how much time you should spend learning new skills—and why it works

This is the ultimate way to make sure your 20% time doesn’t go to waste. Figure out the minimum benefit you’ll get out of a given situation or opportunity, even if nothing else breaks your way.

It might be exposure to a new industry, making connections in a different region, or practicing valuable skills like public speaking and clear communication.

If the minimal outcome alone sounds intriguing, then the project is likely a good bet.

Protecting your 20% time is like maintaining a diet: It’s good to be disciplined, but sometimes you need to bend the rules and be flexible.

Client emergencies or impromptu staff meetings may prevent you from spending the time you’ve allocated in your calendar, and that’s okay — as long as you make a point to reschedule it and keep that commitment.

The point isn’t that you have to do your 20% time every Thursday afternoon; the point is to do it, period.

It takes effort guard your 20% time, and it’s a lot harder to maintain that willpower if all you’re doing is endless homework and rigorous training sessions.

You may need a hardcore dose of that willpower periodically because in any discipline, there are some challenging elements you’ll have to master. But if difficult tasks are the only thing you do, you may grow bored or frustrated and want to quit.

Just like with an investment in the stock market, when you invest time in your 20% projects, the power of compound interest is dramatic. What at first seems small and meaningless can enable you to put massive distance between you and your competitors. 

The gift of the 20% time, especially when we think in decades, is that even if we ultimately change plans or decide on a different course, the small steps we take now compound over time and give us more options in the future.