Your social calendar might be sucking the joy out of activities that are supposed to be fun or relaxing, according to an upcoming paper co-written by a professor who studies time management.

The paper argues that when a leisure activity is planned rather than spontaneous, we enjoy it less.

That’s because we tend to mentally lump all our scheduled activities in the same bucket — whether it’s a dentist appointment or grabbing coffee with a friend. And that makes the pleasurable activities more of a chore.

“It becomes a part of our to-do list,” wrote Selin A. Malkoc, one of the study’s authors, in an email to The Washington Post. “As an outcome, they become less enjoyable.”