While you might think that working all the time will help you be a step ahead, the reality is you’ll get diminishing returns in your productivity and performance in the long run. Worse still, you will be stressed and exhausted, and your health and even your family relationships will be affected because you simply neglect other aspects of life trying to make that project perfect.

Opportunity cost is usually expressed in terms of how much time and value must be forgone to pursue an opportunity

Must-haves: Critical to achieving the objective. Without it, the outcome is meaningless.
Should haves: Important but not critical. However, leaving it out may lessen the impact of the final result.
Good to haves: Having it is nice, but not including it won’t have any negative impact on your objective.

It states that 10% of your actions account for 90% of your results.