Such a great subject! I love that you are including practical applications to your aikido techniques such as overcoming fear! This has been a very important part of my training and such an important part of life. Fear is certainly a terrible master to have yet, when controlled, can become a useful servant (yes, I am paraphrasing and stealing from my teacher
) I don't know of any specific technique that I've done to help me overcome fear (save maybe...maybe, jumping breakfalls) but more so an attitude toward training. Fear is a brother to indecision and brought about by uncertainty and lack of confidence. My martial training has helped me develop a martial spirit which, in turn, has helped me mitigate fear in my life.
I attribute a combination of martial philosophy discussion and training with intense spirit to this. Perhaps 'hajime' practice helps in its own way. This is training where you and a partner train in a very intense manner. The uke constantly attacks, with no breaks, going at absolute full speed. No thinking, no hesitation, just completely putting yourself out there, out of body, and completely giving yourself over to your partner. I feel regular training like this is one way to develop spirit...constantly pushing yourself to go longer, and harder, than you thought possible. This does two things; forces the two people training to have no time for fear, and also forces them to trust in their technique and abilities...developing confidence in themselves.
Secondly, it is a great way to completely break down physical training. once the physical aspect of training is torn down...reaching a physical limitation...you only have your spirit to drawn on. This is what forces you past physical limitations and helps develop spirit. Training this way...regularly...develops this spirit just like lifting weights develops muscles.
I will directly relate this to recent experiences in my life. I was once on a night patrol through some opium poppy fields in Afghanistan. Some Headquarter folks came from their base to our area out in the boonies. They wanted to go on a combat patrol to get some combat experience under their belts. In infantry unit or, in our case, a reconnaissance unit Headquarters personnel are typically support people vice actual recon guys. A few hours into the patrol, some of these HQ guys simply sat down and gave up...they could not continue. This absolutely blew my mind! They were basically saying they would rather die, stopping mid patrol, than continue on. I really could not wrap my head around it, and it took some convincing that people in ranger file had simply stopped and refused to move! They were tired, scared, and let fear permeate their soul until they could no longer had physical control of themselves. Now, in the Marine Corps, Recon Marines train to develop this type of 'martial spirit' regularly. They don't vocalize it the same way martial artists do..but that type of training is there, and practiced regularly. They go on practice patrols to the point beyond exhaustion, tread water for ungodly amounts of time, do 1000 burpees...simple things that sound silly but help develop one's spirit. How this is different from me is as follows; while I am a Marine, I am not a Recon or infantry Marine so am not subjected to the same kind of regular training. I was a support guy embedded with a Recon unit for their deployment. I attribute my ability to have the same mindset and abilities through the conduct of an 'outside the wire' deployment to my aikido training (it certainly goes well beyond physical fitness or training. Some of those people that quite can prob run faster and do more pullups than me, or the other guys I was embedded with).
During training, training like 'hajime' practice and other training, we are often told to train with the mindset that we would die if we stopped...shinken shobu...train like you are in a sword duel to the death. While not actually facing life or death situations in a dojo, I feel like this development can still take place as your subconscious isn't aware if you are actually in mortal danger in the dojo.
Typically before stepping off on a patrol I would get apprehensive bordering on fear. There comes a decision point where you feel fear creeping in and you either allow it to come to life, or simply choose to drop it. This 'choice', while simple, is not necessarily easy. However I feel that applying this mindset to budo training, again, helped me to have no difficulties in deciding to ignore the kindling of fear inside me. Sayings, or ishi, such as malobashi! (just do it!) and ken o fumo (step on the sword) would come to mind and I simply decided to not allow doubt, fear, and uncertainty control me. Its an amazing feeling, but as soon as you realize you have this choice the 'going down a roller coaster hill' feeling in my gut was replaced with a sensation of warmth and confidence.
I hope this isn't too off-base, and I apologize for its length. I know I am not the best writer and maybe I can answer any questions with more clarity...but I do hope this relates well to the idea of overcoming fear as a practical application to budo training. It is something I am truly passionate about and is critical to the purpose I sacrifice so much for my martial arts training.
I hope your training is beneficial and you have a great time teaching class in your sensei's absence...I hope you understand what an honor it is for your teacher to ask you to fill in for him/her! Give my best to Sato Sensei and I wish the AWA prosperity!