Unless you are out getting in fights with people all of the time, you can't. What you can do is to put yourself into situations in which you are under a lot of pressure to perform well, even when things may go wrong. That is the gist of this article. A excerpt is provided below.
The Lessons of Embu
In martial arts training it is essential, in my opinion, to have some arena in which one is forced to put oneself on the line. Arts that have shiai provide plenty of opportunity--believe me, there's quite a lot riding on the line when you face an opponent trying to stab you with a bayonet. But in the classical arts, and arts like aikido that in general do not have competition, we must find other ways to push ourselves to the edge. Promotion examinations provide one sort of opportunity to face fear of public failure, to learn to control natural physical stress reactions, and to continue come what may. But for most of us, exams are few and far between. Demonstrations, then, are perhaps a sensible alternative.
In some styles of aikido (Tomiki aikido in particular, but by no means exclusively) formal kata embu kyogi, or kata demonstration competitions, are used to provide this sort of training. I am coming to the conclusion, however, that the resulting emphasis on what the technique and overall performance looks like in order to win a prize is misguided. I am a (now retired) kata embu competitor, and have competed quite successfully in Japan, the United Kingdom, and the United States, in sometimes as many as four events per year. There is no question that I have gained from my experience--I have no problem with giving a demonstration of anything that I know in any art that I have studied at any time, and remain unperturbed when not all goes as planned.