Multiple Forgone Job Opportunities and Economic Profit I'm told that forgone job opportunities are implicit costs, to be included in calculating economic profit, but I can't seem to see how I could list and consider many different forgone opportunities. My question here is how do we do so?

For example, if I have a piece of land or big city real estate, there could be a great many different uses for it. If I considered each of these forgone opportunities an implicit cost, I would think the expression of my economic costs would be useless to me. 

So I suspect that either I'm suffering from an oversimplified ECON101 explanation of implicit and opportunity costs or simply an incorrect one. Any references would be appreciated.
We don't use all possible opportunity costs. We only use the cost of forgoing the next-best-alternative.