Blowing the Bloody Doors Off by Michael Caine is one of my best-loved books, not just because he's one of my favourite actors but because the book is littered with so may pearls of wisdom that can be applied to a wide range of situations.
In chapter 4 Caine talks about the importance of learning your craft and the importance of preparation.
When we observe anyone at the top of their game, whether they are athletes, coaches, business owners, artists or performers they make their 'performance' seem effortless. It's not because they have some special talent that they were blessed with from birth (a convenient excuse we like to tell ourselves to disguise the fact that they are bloody hard workers). In every case there will have been a significant amount of preparation taking place behind the scenes.
My best coaching sessions are the ones that I've planned properly. My best conference presentations have always been then ones where I've taken the time to really work on my delivery. My best performances in an adventure race have come about after significant planning.
If you are not happy with your level of performance, maybe it's time to look at the time (or lack of it) that has gone into your preparation.
As Michael says "you should be so familiar with what you're doing that it seems effortless."
Source - Michael Caine, Blowing the Bloody Doors Off