In the pursuit of a principle-driven life, anything can be a friction force. Things like kindness are perceived as good and desirable qualities, but easily become friction forces in certain contexts.
Kindness is frequently the reason why people don’t tell necessary truths. A desire to be kind, and not appear insensitive, is what slows or stops people from saying what needs to be said. Kindness can be a friction force for truth telling.
A friction force isn’t necessarily something that generates friction for everyone or generates friction by nature, it just creates friction for you. Anything that affects your consistency in bringing discipline to a specific principle is a friction force. Even if it’s another principle, like in the case of kindness and truth telling.
Here’s a list of principle + friction force relationships I frequently observe: