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

The best advice I ever got was at a chow hall in Korea. It was from an older gentleman who sat down to eat breakfast next to me. We were on a small post, CSCT 3, maybe 45 Americans with an COL in command during day to day. This was right before a UFL exercise, and we had III CORPS Arty commander and DC on post. Well the gentleman started talking to me and asked my goals and gave me a lot of advice about enjoying my experiences and keeping my career in my control. I though little of it because we always had tons of visitors. At the end of the exercise I see the guy put a not and envolope on my door and go back into his room which was across the hall from mine. That’s when I put two and two together, my breakfast was with the DC of III Corps. Was a great memory that left a strong impression on a young PV2

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.