Oddly Wired
← all facts
motivation

You value things more after working for them.

Effort justification leads you to increase your valuation of a goal simply because it was difficult to achieve.

When you endure pain or high effort for a result, you convince yourself that the result is objectively valuable to justify the cost. This protects your ego from the realization that the effort might have been wasted. You become deeply attached to the things you have suffered for.

The difficulty of the path determines the value of the destination.

Where this comes from

Study
Festinger, 1957
What the check found
Festinger's 1957 theory predicted this effect, and it is widely cited as the origin of the concept, even if later experiments (like Aronson & Mills, 1959) are better known for the laboratory demonstration.
Confidence
Solid, with limits

Related

One of these every day, and every one names the study it came from. When a finding is contested, it says so.