Huh.
Back in the day when I shared motivational thoughts with student-athletes, the topic of fear and self-doubt came up quite often.
Fear and doubt can be a sensation just as overwhelming alone as it is on a field surround by teammates, opponents and hundreds of spectators. It can be perceived as an inherently dual natured calamity; failing not just yourself, but all those around you. If there is a more potentially lethal double edged sword, I cannot offer one. A predicament that often leads to absolute failure.
Not trying.
This is cloaked by “self-assuring” monologue of sorts, one that is determined to convince you that you would have blown it anyways, so why even try? It wasn’t for you, nothing would come of it and hearing the chorus of “I told you so” externally and internally would make things even worse.
Mr. Shakespeare addressed this conundrum in a most succinct fashion.
“Our doubts are traitors,
and make us lose the good we oft might win,
by fearing to attempt.”

Essentially, self betrayal lay in the decison to avoid the attempt altogether. Losing in it the good to come for all, us included.
As a result, self treason doth never prosper.
Sorry for making it one of my coachisms, Mr. Harington.
At least I tried.