The Opportunity/Obligation distinction distinguishes between

  1. things we do because they feel like obligations, responsibilities, virtuous actions our ideal self 'should' take, and related frames.
  2. things that we are excited to do, that feel like opportunities to improve something we care about.

This is related to towards vs away framings, and carrot vs stick.

Semantic inversion: the should/could inversion is a handle for remembering this concept, reminding you that many instances of the word should can be replaced with the word could.