Flow Requires Balance Between Challenge and Skill Level
Being in the flow state requires a balance between the challenge of the activity and the skill level of the performer. Too much challenge results in failure and anxiety, and too little challenge results in boredom. We experience peak motiviation when working on tasks that are of just manageable difficulty: right on the edge of and slightly beyond our current abilities.
It is important to continue to advance in small ways and continue improving and challenging yourself to keep engaged. Behaviours need to remain novel in order for them to stay attractive and satisfying. Without variety, we get bored (although there is value in working through the boredom and just showing up).