You say you want to start a company, but do you really think you have what it takes? You may be a detail-oriented geek or a visionary, a hyper-active multi-tasker or an obsessive, and have an equal chance of success. But there are certain character quirks that entrepreneurship simply demands. After building startups myself and investing in many others over the past 20 years, I hold these four traits to be non-negotiable.

1. You must be up for an adventure.
Starting a company or investing or joining a startup is like embarking on a four-week backpacking journey with enough food for one week. You don’t know where you or your company will be a year out; you don’t know how many people will be with you. You have to be comfortable with uncertainty. You should a clear vision on the end point, but the journey is very unknown.

Look back at the times in your career when the future has been uncertain. Were those the times that you thrived? Were you the irrationally positive person in the room? Were you the one firing up the team when everying seemed bleak? If you were not, let me say this: You at least have to be smart (and honest!) about your shortcomings, then hire someone who can do that for you.

As an investor, I prefer to see an entrepreneur who can do a little bit of everything without stressing when things fall outside his or her comfort zone. But I also recognize that a crack team of founders can be just as effective (if not more effective) than a one-man show.

2. You have to be patient.
Success will not happen overnight. This may be hard to believe if you’re constantly reading tech blogs, in which it seems to be gospel that billion-dollar valuations come to everyone who shows up. But the fact is, the companies that have endured took years to build. Starbucks opened in 1971, and eight years later they still had only operated a handful of stores. Spotify has been around since 2008. Amazon took 9 years to turn a profit.

You need to understand that the problems truly worth solving, the big industry problems, will not be wrapped up neatly in a year or two. It may take decades, and you will almost definitely have to make many adjustments to your initial vision. You’ll have to persevere through unfavorable conditions. But if you don't easily discourage, you will always have a better chance of succeeding.

3. You can’t be a perfectionist.
This is not a business where you will be able to spend all of your time and energy fixing one problem.

Good entrepreneurs can find a way to jump into the fray and start implementing ideas and solutions, even if they don’t have all the answers. You have to be comfortable covering a wide territory, with knowing a little bit about a lot of things, rather than a great deal about one thing. Compromise is essential for survival.

If you can easily check off all the risk factors when looking at a problem, it’s probably not a problem worth solving. So embrace the messiness. You’re going to learn more about what your battle plan should look like, and what challenges you need to expect, as you go along.

4. You have to be your company’s best sales person
Finally, it’s essential to remember that you must be, at your core, a great salesperson. You need to be able to sell your vision to potential partners, investors, and customers. If you can’t successfully do this, you’ll have a tough time getting very far. You’re going to be the first person to introduce the world to your product, and first impressions are important. Everyone wants to hear about your passion from you.

Learn the most common questions and reservations that people will have. They’ll want to know why what you’re doing is valuable. Cut out the jargon and speak to the heart of the matter. Start at the core, and then fill in the details. You have to hook them with the big picture before they can appreciate the nuances.

You wouldn't be reading this if you didn't have great faith and excitement in your idea. But you don't have a real business until you can enkindle that faith and excitement in others.