In the spring of 1966, a man named Ernesto Miranda was arrested in Phoenix.

There was just one problem.

This post originally appeared onJames Clears blog.

When the case went to trial, Mirandas written confession was used as evidence.

The Supreme Court had just created a bright-line rule.

The Power of Bright-Line Rules

A bright-line rule refers to a clearly defined rule or standard.

It is a rule with clear interpretation and very little wiggle room.

It establishes a bright line for what the rule is saying and what it is not saying.

The Miranda ruling is one example.

Most of us, myself included, could benefit from setting brighter lines in our personal and professional lives.

Consider some common examples:

We might say that we want to check email less frequently.

We might say that we want to drink moderately.

We might say that we want to save more for retirement.

We might say that we want to eat healthier.

But what do these statements really mean?

What does it mean to check email less frequently?

Are you going to take a stab at be better about it and hope that works?

Will you set specific days or certain times when you will be unavailable?

Will you check email on weekends?

Will you process email only on your machine?

What, exactly, is moderate drinking?

Is it one drink per week?

Five drinks per week?

Ten drinks per week?

We havent defined it, so how will we know if we are making progress?

What does it mean to save more?

More is not a number.

How much is more?

When will you save?

What does eating healthier look like on a daily basis?

Does that mean you eat more servings of vegetables?

If so, how many more?

Do you want to start by eating a healthy meal once per day?

It can be easy to make promises like this to yourself, but they do not create bright lines.

Fuzzy statements make progress hard to measure, andthe things we measure are the things we improve.

Now, do we need to measure every area of our lives?

But if something is important to you, then you should establish a bright line for it.

Consider the following alternatives:

I only process email between 11AM and 6PM.

I enjoy a maximum of two drinks per night.

I save $500 per month for retirement.

I eat at least two types of vegetables per day.

These statements establish bright lines.

These statements make action steps precise and obvious.Vague promises will never lead to clear results.

My friend Nir Eyal proposes a similar strategy that he calls Progressive Extremism.

To explain the concept, Nir uses the example of being a vegetarian.

You are establishing a bright line on that topic.

Over time, you might progressively move your bright line forward and add other behaviors to the mix.

I dont eat red meat or fish.

And so on.)

Bright lines help you avoid making just-this-once exceptions.

Instead, you are following anew identitythat you have created for yourself.

With bright lines, the decision is made ahead of time.

Thousands of people have attended his online seminars onHabits,Willpower, andProcrastination.

Image byPan JJ(Shutterstock).