Principle with an "le"

What is a good principle to keep? One deeper than simple morals. One that you would want to share with your kids and grand kids. One of mine would have to be you can't be rewarded for work you didn't do. It doesn't feel good recieving credit for work you didn't complete to the best of your ability or just wasn't yours at all. I find this the reason many group projects are flawed. Another one I think is a good one to keep is never lower yourself to the level of someone else, and this is a big one to me because it is the one that comes up the most in my life. My mom always taught me that no matter how someone is treating you, you should never stoop to conquer. So essentially I have to try and stay calm and sensible while people attempt to break me down. In closing I guess the best principle to keep is to stay strong. Stay strong through any and everything life could ever throw at you.