Most people love a good kiss. A prerequisite to a good kiss is good breath. In order to have a pleasant breath most of us use toothpaste and a toothbrush. Now imagine with me someone who discovers the joys of kissing. This person, let's call her 'Joy' loves the person she kisses, let's call him 'Joe'. Joe is Joy's husband.
The two of them is madly in love and they show it by affectionately kissing each other. To make the experience pleasant they usually brush their teeth so that they can be on the same 'breath length'.
This worked out well for them, that is until Joy (if you want to you can exchange her name with Joe here) became obsessed. Her (or his) obsession obliterated all the enjoyment from the kiss. What was her obsession? It wasn't another man (or woman). It was her obsession with her toothbrush.
When the kissing started it usually took her 30 seconds to clean her teeth. These days she obsesses for almost 10 minutes over the state of her breath. When she finally feels comfortable with her breath, she is so exhausted by the cleaning process that she's not in the mood for kissing anymore (and Joe is usually already in a different place). The impulse of kissing and the invitation to intimacy translated into a rigorous obsession with a clean breath and a preoccupation with the toothbrush.
This same thing happens when we get stuck on disciplines and stop enjoying intimacy with God.