General Jim Mattis, 40 years in the U.S. Marine Corps.

How do you keep improving as a leader to meet the demand of each role in your career? We all get promoted, you have different roles to play.

How do you stay teachable as a leader?

I think the most important thing here, Joel, is that you have to assume you must keep improving.

If you make that your decision that you must improve,

if you look at every week in the Marine Corps

is your last week of peace

and you must be better at the end of this week as a warfighter,

then you'll push yourself on your three-mile run down to 18 minutes

and you'll accept no excuses.

You'll push yourself in 21 pull-ups, and you'll accept no excuses. You'll push yourself 21 pull-ups and you'll accept no excuses.

You'll push yourself to read the Commandant's reading list.

You'll push yourself that when the things are going tough in the field,

you keep your spirit up and you're the man everyone can turn to

knowing that you don't give up.

And you just keep improving every day with the assumption that if you're going to lead

more Marines in the future as you get promoted, they expect you to be the physically toughest,

the mentally sharpest and spiritually, just the most undiminished person that nothing, not cold,

not rain, not enemy situation, not frustrating rules can get you down. And you just maintain

this body, mind and spirit improvement at all times. You stay teachable most by reading books, by reading what other people went through.

I can't tell you the number of times.

I looked down at what was going on on the ground or I was engaged in a fight somewhere

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