I am a Millennial.

Every single day, I see people on both sides of the spectrum. I have friends who are absolutely killing it: own their own companies, travel the world, are smart with their money, reinvest heavily in themselves and their interests, etc. And I also have friends and peers who, in all honesty, talk the talk a lot more than they walk the walk. That doesn't make them bad people--to each their own. I'm just very aware of why they struggle so much to find their stride.

Here's the harsh truth, and the 1 mentality difference between the 20-somethings I know who are living life on their own terms, and the 20-somethings who wake up every day stagnant and unhappy:

Superstar Millennials don't take no for an answer--ever.

When an obstacle presents itself, there are two ways of looking at it.

The first is to say, "That's a wall. I can't break down that wall. I probably won't be able to break down any wall. I guess I'll just never be successful."

The second is to say, "Hmmm, that's an interesting wall. I wonder what I can do to get through it."

Every single superstar Millennial that I know, approaches every obstacle with that second mentality.

To them, there is no such thing as "I can't." They don't take "no" for an answer. Failure is not an option, and sitting there sulking about it is a poor waste of time.

Instead, they start asking themselves questions in an effort to reach a solution. They assess the obstacle. They reach out to people who have encountered that same obstacle before. They study it. They try and fail, try and fail. They bash their heads against it over and over again until, finally, they break through.

Meanwhile, everyone else is still sitting around, calling themselves worthless and unsuccessful.

It's unfortunate that our society doesn't nurture this mentality earlier in life. School doesn't encourage this way of thinking. If anything, school promotes this idea that, "If it's too hard, you're probably doing something wrong."

Superstar Millennials live by an opposite mantra: "If it's too easy, I'm probably not challenging myself enough."

If you want to be young and successful, this is the mentality you need to adopt.

It's crazy to me how many young people, peers of mine, talk about wanting to be successful or wanting to work for themselves, be their own boss, travel the world, make tons of money, change industries, make an impact--and then when push comes to shove, they're the first to crawl up in a ball and give up.

But look at any success story in history, and it's not inherent talent that defines who rises to the top. It's work ethic. It's this mentality of not taking "no" for an answer, and doing whatever is necessary in order to move forward.

I have always been a believer that it doesn't matter how you learn this mentality, as long as you learn it. If you need to play a sport to learn it, great. If you need to join a club, great. If you need to be part of a shared workspace and be around other hungry entrepreneurs, great. If you need to spend hours by yourself, working in silence, great. There is no right or wrong way of learning how to have this sort of disciplined mentality. As long as you learn it and put it into practice.

I would encourage any Millennial who wants to do something special with their lives to think hard about how to nurture this way of thinking.

The next time you find yourself faced with an obstacle, try to notice what your response is.

And if it's, "Man, that's a big wall. I'll never be able to get through that," then know what you need to work on.

You need to work on your mentality.