When is a person Mikayem a Mitzvah Lo Taaseh? 1. If I’ve never had a desire to murder anyone am I constantly "Mikayem" the Mitzvah not to? 2. Conversely, if I have a slight desire to eat the food of a non-kosher restaurant as I walk past and smell the pleasant aroma, but resist, have I then been Mikayem the Mitzvah not to eat non-kosher? 3. Or when I’m in a group of friends chatting, and the conversation turns to Lashon Hara, and I have a great desire to participate, but instead find something else to do, have I been Mikayem a Mitzvah then?

Usually the term "Mekayem" is used in reference to a positive commandment or act. However, refraining from committing an offense, i.e. a negative command is a praisworthy act and brings reward.