I have a handful of go-to challenges I give everyone from the NFL athletes and Special Forces soldiers who train with me at Gym Jones, the worlds most hardcore gym. These challenges build a killer instinct that helps you achieve any goal.

My favorite test of psychological will is to set a rowing machine for 2,000 meters and have you row for time. It also tests your strength and cardio, making it a great gauge of your holistic fitness.

The test works so well because you cant cheat. The only way to gain an advantage is by pushing harder. The clock is unbiased and unforgiving. You can't pass with half-ass form or reps.

The time I want you to finish in: 7 minutes.

Seven minutes or less tells me that youre not only in good shape, but that youre also willing to silence your mental demons, go all out, and keep getting better.

Of course, it's OK if you cant finish in 7 minutes. The point is that you truly give the test your all, and continually train to finish below the time limit. Once you nail that goal, keep going. I regularly see people finish in the low 6-minute range. (All other things being equal, taller, heavier people generally log faster times than shorter, lighter people.)

When you take this test, youll probably think the first 500 meters is relatively easy. But halfway through, your mindset will change.

This is when your wheels begin to fall off, because youre left alone with your thoughts. Ive watched numerous people go through this, and it quickly progresses from Im not going to make it to Im going to die if I keep going.

A good test of whether youre going hard enough is to ask yourself: Do I want to quit right now? If your answer is no, you arent rowing hard enough.

I can tell you this: If you fight to the end, youll become something more. The people who succeed are always better for it, and it usually unlocks the door to success in many other areas of their training.

Thats why the 2,000-meter row challenge and a handful of other key fitness tests are included in my new Men's Health book, Maximus Body . Youll find the tests peppered throughout the 12- and 26-week workout programs that I give to people who need elite fitness and a never-say-die attitude, like pro athletes and Tier 1 military assets.