As an entrepreneur, one of the hardest lessons you will ever learn is the value of saying “No.”

In the beginning, it’s all “Yes.” You say “Yes” to everything. And there is a time and place when this sort of mentality works. It works really well, actually. Because it teaches you, quickly, what is worth your time and what isn’t.

However, the real takeaway has a lot more to do with prioritizing your own ambitions. By saying “Yes” to everything, you eventually run yourself thin. You feel like the world is spinning around you and you’re not sure which direction to go. And it’s this lack of focus that actually brings to light the bigger lesson: Everything comes with an opportunity cost.

Whenever you say “Yes” to something, you are, at the same time, saying “No” to something else.

Eventually you come to realize that by saying “No,” you are really saying “Yes” to yourself. It’s an opportunity cost for you to spend your time doing something for someone else when you could be doing it for yourself. And so by saying “No,” you are now freeing yourself up to do what you need to do, for you.

1. Saying “Yes” To Everything Is Short-Sighted Thinking

A lot of people say yes to things they’re not excited about simply because they either need the revenue or feel like they have to take anything and everything that crosses their path. This is very short-sighted thinking. Sure, sometimes you need to take on projects for the time being, but you should only do so with a clear game plan for how you’re going to continue building what it is you actually want to build for yourself in the long run.

2. If You’re Not Excited In The Beginning, You Probably Never Will Be

If you aren’t excited about the project from the get-to, that feeling will rarely change. You know deep down whether a project excites you or not. Remember: Opportunity cost. If you say “Yes” to too many things you aren’t excited about, then how much time are you going to have available when something comes along that does excite you?

3. The Smallest Projects End Up Costing You The Most

As my mentor once told me, “Anytime someone says quick and easy, I know it’s going to be long and difficult.” This ends up being more true than people prefer to admit. The smallest projects can end up costing you the most time—and that’s what you need to always think about. Be aware of the time investment, not just the revenue.

4. Your Value Increases Based On Your Exclusivity

People tend to forget why luxury brands work: Exclusivity. And in order to create that sort of luxury value for yourself, you can’t be saying “Yes” to every little project that comes along. You have to realize that in many cases saying “No” can end up increasing your value. Why? Because you don’t just work with “anyone.”

5. Time Spent Working Is Time Not Spent Practicing

If your dream is to be a designer, for example, but you continue to pack your days full of projects as a copywriter, then when are you investing hours into becoming a designer? Most likely, you’re not. Too many people fall into this trap. If you want to shift your direction, or increase your value, or grow professionally, there are skills you will always need to continue to master. And in order to master them, you need to practice. By saying “No” to certain projects, you will have more time to invest in yourself.Opinions expressed here by Contributors are their own.

Nicolas Cole is a writer and essayist, and Top Writer on Quora with over 10,000,000 views. His work has been published in Time, Forbes, Fortune, Inc., The Huffington Post, Business Insider, and more. He is a columnist for Inc Magazine and is best known for writing true stories about self-development. You can follow him on Twitter @Nicolascole77