What is the best lesson an NCO/Officer has ever taught you?

As an aside, I was newly appointed as a warrant, Previously I was a SFC. When I was in Korea, I saw the troops with my Senior NCO. I walked up and asked what the problem was, She stated, "This is NCO business" Message received, Know your lane!

Responsibility to my troops just as important as my responsibility to my superiors.

Don’t yell so much, sir!

I was a SSG E-6 applying for an Active Duty ROTC Scholarship. I did it on my own. My Battalion Commander, LTC Douglas Tademy, told me “God helps those who help themselves.” He subsequently wrote a letter of recommendation for me. I’ve never forgotten to ask senior ranking people for help after that.

One of the most important lessons came from a 1SG. He had a CSM tell him to counsel me bit before doing so he asked my side of the situation. After hearing both sides he knew a counseling would not be needed.
We talked about this and he told me every good leader takes the time to hear both sides of an issue when it comes to Soldiers. I've used this advice as a Sr. NCO and as a Chaplain.
Best advice I've ever received from a military leader.

one of my early mentors CSM Bjornson told me to never burn a bridge in the Army, you never know when you will be back working with someone, always offer your help or assistance to other NCOS you never know when you will need help yourself.

A Captain once told me If you want me to be on the plane when it crashes, ensure I am on the plane when it takes off..In other words if something bad may happen make sure I hear about it from you, not the General. I was the 1st SGT

If you lose your cool and get pissed off in peace time, non-emergency environment; what message are you sending your Marines about how you will handle the stress of combat?

The best advice I ever got was from a Staff Sergeant by the name of Fred Sames (RIP) who told me that training is hard enough without SNCOs throwing their weight around for the hell of it. He said you don't have to train to be uncomfortable, that comes naturally with the job.

What I learned from a battalion commander when I was a young buck sergeant. Every soldier has a sergeant. The BN CDR has the CSM, CO has 1SG, a Private has his Team and Squad leader. NCOs run this Army every day so if a young LT fails his NCOs have failed. We all know it’s the NCO Corps that run the Army but he put the fire to our feet that if there was a failure it’s because a Sergeant wasn’t doing his job. Every Solier has a Sergeant!