My youngest son is a high school junior. He was recently assigned to have a parent write him a letter of advice, similar to the advice Polonius gave Hamlet. Here's what I wrote him. Comments welcome.

Dear son,

Your grandfather taught me a great deal during his life, both by precept and by example. I've always tried to do the same with you and your brothers. The idea that I'm supposed to write down all my distilled life experience and advice in a single letter is pretty daunting. What if I leave something important out, like "always brush your teeth?" I'll do my best to stick to the most important things in this letter but it may get kind of long.

As you know, I have had the good fortune to travel the world, work in a fascinating career, serve our country in the military, and meet fascinating people from all over. Here's what I think you need to know.

"Brush your teeth and pay your mortgage early." This was one of your grandfather's favorite pieces of advice. When he was a little younger than I am now, he had all sorts of dental problems (including bad gum disease that led to him having several teeth pulled). Don't be that guy. More generally, two things: take care of your body and be very, very wary of debt. Lift heavy weights to strengthen your body; find an endurance sport you enjoy to complement that. And seriously… brush your damn teeth.

Find your mission. Throughout your life you will often wonder why you're here or what the point of your life is. That's something only you can answer. My mission is to be the best man I can be and to live the best life I can. That would still be true if I had a different career or different life circumstances. "Best" means trying to live up to the standards I set for myself, some of which are outlined here. Your mission shouldn't be just "make money" or "get women." Focus your mission on who you are (or aspire to be), not what you do. No one but you can determine what your mission is or whether you're accomplishing it.

Always add value. In every personal or professional relationship, you should always be able to identify what you're bringing to the party. Be the kind of man who has something useful to contribute in every endeavor: your knowledge and skill, your physical strength and endurance, your stability and reliability, your sense of humor, your work ethic, your love… the list goes on. It's OK to feel like you don't have much value to add, or that you don't have all these things right now-that's a sign that you need to work on developing them, which we all need to do. Find or enhance your skills, talents, and capabilities so that you can add value. Other humans, whether employers, friends, or potential lovers, will always seek the highest value they can find.

Always expect value. Over time you will learn to identify what value others bring to your life. Watch carefully what others add to your personal, family, and work relationships. If they are not providing the value you need, know when it is time to move on. Your friends, coworkers, acquaintances, and lovers over the years will each show you through their actions what they can and will do to enliven or improve your life. Ever have a friend who always took attention, time, and energy but never gave any back? Avoid that type of person. This is not a "what's in it for me?" piece of advice, more a recognition that anything which does not push your life upwards will drag it downwards.

Never stop learning and growing. You and your brothers like to make fun of the fact that I didn't start liking avocado or sushi until my 40s, or that I didn't run my first triathlon until age 45. But that's objective proof that you can always try new things, learn new things, and grow as a man. As you grow you will find new opportunities, new interests, new people, and new value to enrich your life. When I was your age I had no idea who I would be in 2018. In just my 40s alone, I have drastically improved my physical fitness and health, made amazing new friends, found hobbies I never would have thought I'd enjoy, traveled to exotic places, and had remarkable experiences with my sons. Never stop. You can't achieve your mission if you don't know anything.

Work hard and earn your leisure. If there's work to be done, do it. You're really good about not procrastinating your schoolwork. I hope you never lose that trait. The world is full of people who are content to sit on their asses playing Xbox or reading crap on the Internet, then complain that they have a crappy job, no worthwhile relationships, and no meaningful purpose in life. You may even know some of these people. Don't be one. Playtime is awesome once you have put in the work-and that includes exercise and self-improvement, not just the literal work you do at school or at a job. Your ability to accomplish your mission is directly tied to whether you do the important stuff first or turn into a Dorito-eating couch-locked neckbeard.

Seek the best. You wouldn't try to fuel an airplane with dirt and rocks. Don't fuel your mind with crap. There's nothing wrong with enjoying good entertainment but don't waste your time with stuff you know (or suspect) is low-quality. Stay away from crap on the Internet. Read the classics. There's a reason why people are still reading Epictetus, Seneca, Shakespear, Dickens, and Carnegie hundreds or thousands of years after their deaths. Read non-fiction books on topics that interest you regularly. See what you can learn from the experiences, knowledge, and lives of others. Someone who passively consumes entertainment can't add any value to his own life or anyone else's.

React to what people do, not what they say. The world is full of people who will say one thing and do another. Want to know if someone is truly your friend, or really loves you, or actually has your best interests at heart? Ignore what they say and watch how they treat you and how they behave. Watch how people treat others who are less powerful than they are-a waiter, a clerk, a subordinate at work, a child.

Be your own man. The world is full of people who will tell you how to live your life. There is nothing wrong with listening to their advice, then evaluating whether that advice is good for you or not. You are ultimately the man who has to look at himself in the mirror each day and judge yourself. There are plenty of other people who will judge you. But you know what 311 said: "fuck the naysayers." Also, they only entered in one contest that they made up themselves, you feel me?

Do what is right, and stand up for what is right. At any given moment, you will almost always know what the right thing to do is. Sometimes you have to figure out the least-wrong choice from a series of bad alternatives, but usually not-it will usually be pretty obvious. Never tolerate or accept bullying of yourself or others. When you see a wrong being done, correct it. That doesn't mean arguing with people on the Internet, by the way, or defending people who have acted badly and are now facing the consequences of their bad actions.

This seems like a lot of advice, and it is. I encourage you to go back and look at Ben Franklin's system for journaling, where he identified a single aspect of his mission to work on each day, each week, and each month, and then tracked his progress. (In fact, I strongly advise you to read his Autobiography on general principles.) You don't have to-and probably can't-implement all this advice at once. Pick one piece of advice to implement at a time and then focus on it. Just like your lifts are progressing in Stronglifts, or like you get more fit on the bike, the more of these things you do, the more you'll be able to do.

I love you with all my heart and look forward to seeing you grow into manhood and excellence. I'm always here for you.