Economists have a term called opportunity cost. It describes not the direct cost of buying or doing something, but instead the value of what you could have done instead. What else could you do with that money or that time and would you have preferred that instead? It doesn’t cost you anything to stuff your money in a mattress, but you are forgoing the opportunity to earn interest on it or to buy something you’d enjoy.

When reflecting back on the cost of this project, I am struck that the most painful price we’ve paid has not been the financial cost or the frustration of temporary living or even the physical exhaustion of the work. No, the most painful price has been the opportunity cost.

We planned this for years, and going into this project we knew we would have to make a lot of sacrifices. Other than that one snow day, we have rarely wavered from our relentless pursuit of this goal for one full year. That has meant saying “no” to a tremendous array of things. You can know something intellectually going in, but that’s still not the same as the real world experience of it.

Telling your boss and your colleagues no, I can’t take on that project or serve on that committee. Telling your staff no, I can’t get you that write-up you need or attend that meeting to help resolve your issue with that other department. Telling your friends you can’t join them for trips or attend their parties. Telling your nephew you won’t be at his high school graduation and telling your family you won’t be around to visit them at all this year. Telling your kids no we can’t go to the park this weekend and we don’t have time to make your favorite meal for breakfast. Telling yourself no, I can’t watch that movie or play that game or surf the internet tonight. Its death by 1000 ‘nos’, every one taking a little psychological toll.

Nothing worth doing is easy, and I don’t regret all those little nos that let us live this dream of ours. But be forewarned if you ever think about doing a project this big, whether building a house or writing a book or training for an Ironman competition, the pain will be in the opportunity cost. To be successful requires a thousand acts of will and focus on the end goal. And there will inevitably be days you’ll wonder if its worth it. Hang in there.