When you look at the top performers in every domain, all of them share one thing in common. They live their lives at the edge — at the edge of discomfort.

All growth comes from this edge. It’s a thin line between success and failing.

This is especially apparent in the weight room.

I’ve been lifting weights on and off ever since I was 14 years old. What I’ve learned is that your muscles do not grow if they are comfortable.

If you can lift weight 10 times comfortably, you may be able to maintain your muscles, but they won’t grow.

The reason why?

There is no tension. No discomfort. No need for them to grow.

In comparison, let’s say you lift a weight 6 times comfortably, but the 7th and 8th repetitions are very uncomfortable.

Then, let’s say you find the 9th repetition extremely difficult, as it takes you three times as long to lift the weight.

Your muscles burn like crazy. Sweat drips down your forehead. Your body trembles to keep that weight moving ever so slowly, and then you finally do it successfully.

And then on the 10th repetition, the same thing happens, only in the middle of the trembling and muscle burn, your muscle “fails.” You can’t complete that last repetition and your body is exhausted.

What every weightlifter knows is that, the next morning, there’s a good chance you will be sore. And it is that soreness that signals your body that you lacked enough muscles to handle the load placed upon it.

This is what causes a muscle to grow. Your body builds more muscle in an attempt to handle the load you placed on it last time.

Stated differently, the entire value of a weight training workout is in the final repetition of each exercise — the one where your muscles struggle profusely and then “fail.”

It’s the last repetition, where you struggle, that’s responsible for most of your muscle growth — hence the term “the edge of discomfort.”

The same is true when it comes to developing career and life skills.

When you’re learning a new skill, the place of optimal struggle is one where you’re being severely challenged, but not outright overwhelmed.

If a work project is too easy, you learn nothing. (If a weight is too light, you don’t get stronger by lifting it.)

If a work project is way too hard, you fail immediately. There is no struggle. It’s a complete and immediate failure.

The optimal level of struggle is where a task is 10% – 20% out of reach of your current skill level.

I call this living your life at the edge of discomfort.

All of the top consulting firms base their professional career development around this principle.

At McKinsey, just as I got comfortable with a particular kind of skill, my engagement manager would give me new harder work that I had never done before.

In my entire time at McKinsey, I was NEVER comfortable EVER.

Once I got the basics of analysis, they had me manage clients. Once I could manage clients, they had me manage other consultants.

Once I understood how to do market entry strategy, they had me do sales force performance optimization.

Once I grasped how to do that, they had me do human resources strategy.

Once I understood retail, they had me work with financial institutions. Once I grasped that, I worked in technology.

It was ENDLESS. Never the same challenge twice. Always something new.

The top firms in industry do the exact same thing.

General Electric is famous for doing this.

(Incidentally, more Fortune 500 CEOs were former GE or McKinsey employees than former employees of any other companies in the world.)

When you’re on the “high potential” track (ranked in the top 1% of the company), they rotate you to a new job roughly every two years.

Got good at sales? Great, now do engineering. Ran a finance organization? Good, now run a manufacturing line.

Ran a business in Asia? Great, now do it in Africa. At GE, you do this over 30 – 40 years and at the end of the process, you get Fortune 500 CEO.

Once I was in industry, I crafted my own career path to constantly seek new challenges.

Once I started my own company, I did the same…

Always learn new things… ALWAYS.

Never feel comfortable… EVER.

It’s the only way to grow your skills and your career.

So, my question for you today is: Are you comfortable?

Are you living at the edge of discomfort?

If not, and if you desire to, what can you do to get to your edge of discomfort?

Give it some thought…