MSN.com has a photo essay featuring the collected wisdom of their Facebook fans who answered the question: "What do you wish you knew as a teen?" They got a wide variety of answers, some good, some so-so, some of it just amusing. A couple of excerpts:

Character Counts: This might sound sort of clichéd, but it's helpful to remember: You can't always control what happens in your life, but you can control how you react to it. And it's in those moments that you get to figure out who you are -- and how much it matches up with who you want to be.

Think Of Your Career: When it comes to choosing what to study in college, remember this: Don’t be a history major unless you want to teach history, and don't be a television/radio/film major unless you want to move to New York or L.A. and serve coffee.

Inspired by the question, I tried to come up with my own list of what I wish I'd known as a teen. It was an overwhelming thought exercise indeed. I wish I'd known that God exists, for starters. Also that blue dye sometimes turns your hair green, and that nose piercings hurt a lot more than you think they're going to. I've continued to ponder this question over the past few days, trying to think of the key "what I wish I'd known" lessons I'd pass down to my own kids when they enter their teenage years. Here's what I came up with:

1. There are battles to be fought, and the world needs your energy. When I grew up in the late '80s and early '90s, there was a widespread view that life before age 18 was all about having fun. Well meaning parents told their kids to just have as many good times as possible, in the hopes that this would lead to great childhood memories. The problem was that there was a pervasive sense of purposelessness among kids raised in this view. We teens were bursting with energy and ready to use it for something, even if it meant sacrificing some of our "fun," but we had little encouragement or direction in that department. I wish I had spent more time figuring out what I was passionate about, and had channeled more of my angst and energy into making positive changes in the world. (This will be henceforth known as the Marc Barnes Principle.)

2. Discerning your vocation should be a high priority. Growing up in secular culture, I had no concept of vocation as a state of life (e.g. married life, religious life, etc.), and I certainly had no knowledge that it was even possible to seek God's will for your life. Because of this, there was a certain underlying aimlessness to my years as a young adult, even though I couldn't have articulated the cause. Of course it takes some people longer than others to discover their vocations, and it's possible to live a great life in the meantime. But make sure that you're making this discernment process a high priority, because things get a whole lot simpler when you know which life state you're called to; all other decisions flow from there.

3. You will not find deep fulfillment through a career. In secular culture, there's a pervasive idea that the way you earn a paycheck will also be the way you find lasting fulfillment. This may be true in cases such as full-time clergy or people who devote their lives to serving those in need through nonprofit organizations, but situations like these are the exception rather than the rule. When I graduated from high school, I was fixated on career questions, since I thought that that would define my entire life. I thought that if I could get a well-paying job doing interesting work at company with a fun work environment, I'd be perfectly content. It only took a few years in the workforce to realize that even the coolest jobs get old quickly; there's a reason they have to pay you to do them. Developing a personal relationship with God, serving others, and forming meaningful connections within your community is the way to find that inner peace we all crave; chasing more and more impressive titles on your business card will only lead to frustration and turmoil.

Though there are a few hundred other things on my list, if I had known nothing other than those three things, it could have had a big impact on the rest of my life. What do you wish you'd known as a teen?