Some things you do in life change you forever. Obvious examples may be falling in love, having a baby, graduating college or your first beer. For many--myself included--staring your first business is one of those things. And it was way more impactful than my first beer.

Getting entrepreneurs to accurately describe how it changes you is challenging. It matters, of course, what you do now, how successful you've been and what you did before. But nearly every innovator and venture-seeker I've talked to about this agrees the change is deep and often irreversible.

"It hits you like a freight train. The sudden realization you are an entrepreneur doesn't come on slowly." Says Timothy Forkner (@timothyforkner), CEO of Evangelyze Communications, a Communications Software Firm in Houston. "That long burning feeling of knowing there's a better way, immediately has purpose."

Here are four ways, based on my non-scientific research, I think most entrepreneurs would agree they have been changed by the experience.

You think differently. Being an entrepreneur, going out on your own, not only changes what you do, it's deeper. Entrepreneurship changes the way you think about almost everything.

Once you've spread your wings, you start to see opportunity and challenges around every corner. Every person you meet is a potential customer, investor or brand evangelist. Living in this space for a while, you begin to ask questions and connect ideas in creative (sometimes disturbing) ways: "How can this Greek Yogurt lid leverage SEO production for my medical care client?" Those near you get used to it.

"Too many people associate entrepreneurs as people that just start a business but I don't think that's the case. In reality, true entrepreneurs are problem solvers." says Yazin Akkawi, Co-Founder of Pixl, a UX Design Shop in Chicago. "They're people that find ways to make things better, and businesses are merely a by-product of the value created."

Being out of the box means you can't go back. If you've ever bought anything from Ikea--or anything which requires assembly--you know putting it together can be a pain. But once it's spread out on the floor, try putting it back in the box. I dare you.

That's what entrepreneurship does. Once you see your ideas and your passion spread out on the floor and you see the potential of what can be built, it's really challenging to fold yourself up and go back into a neat box. Corporate life just doesn't fit.

Once passion starts, it can't be shut off. Not everyone should be an entrepreneur. Those that should be, and those who make great entrepreneurs, have a deep, boundless passion. About everything.

That means that once it's unleashed, it can't be shut off. Often times, the best that deeply passionate entrepreneurs can hope for is to direct that energy. That by itself is a challenge--shutting it off is impossible.

Freedom is priceless. That's not a political bumper sticker. It's a truth about having the freedom and flexibility to follow your draems and put your best effort into your ideas.

Even if you make less money than you would being in a corporate corner office (and many entrepreneurs do--for a long time), you can't put a monetary tag on that freedom. Or an emotional one. It's simply not for sale.

So what changes when you become an entrepreneur? It's more than four things, it's everything.