staleness
The state of being old, boring, or no longer fresh.
Staleness is the condition of being old, uninteresting, or no longer fresh. When bread sits on the counter for days, it develops staleness: it gets hard, dry, and less appealing. When ideas or jokes develop staleness, they've been repeated so many times that they've lost their spark.
You can feel staleness in different contexts. A comedian's routine might suffer from staleness if she tells the same jokes for years without creating new material. A friendship can develop a kind of staleness if two people fall into boring, repetitive patterns instead of having real conversations. Even winning can feel stale: a chess champion might feel staleness creeping in after using the same opening moves hundreds of times.
The opposite of staleness is freshness: the quality of being new, exciting, and full of life. Fighting staleness can mean trying something different, taking a risk, or looking at familiar things in new ways. Noticing staleness in your own routines or thinking can be a sign that you're ready to grow, learn something new, or shake things up.