How Will You Measure Your Life? - Clayton Christensen

If you give in to "just this once," based on a marginal-cost analysis, you'll regret where you end up. That's the lesson I learned: it's easier to hold to your principles 100 percent of the time than it is to hold to them 98 percent of the time. The boundary—your personal moral line—is powerful because you don't cross it; if you have justified doing it once, there's nothing to stop you doing it again.

*Decide what you stand for. And then stand for it all the time.*

- Clayton Christensen - How will you measure your life? (Emphasis mine). 

A brilliant article on the impact of marginal thinking tying the critical business concept, which revolutionized the concept of investments in ongoing concerns and how you cannot lose context in the case of disruption to personal life decisions too.