Yeah, what Mongo said!!
Spiritual practice is an everyday thang.
I heartily agree. Although real spiritual practice is also an elusive discipline.
Many people agree that O Sensei (Morihei Ueshiba) was a very spiritual person. It seems that this spirituality expressed itself through his martial art and that was what created Aikido. In this way, Aikido can be seen as a spiritual practice.
However, the spiritual practice of O Sensei also included many other things. Koto-Dama, reading ancient texts or practicing the Omoto religion, were just a few activities that O Sensei did outside of the dojo. For O Sensei and many of us, if this forum is to be believed, spirituality is a "hands-on" activity.
After reading messages on usenet and message boards like this one, many people have written that the "core" of Aikido can be seen in Aiki-jitsu techniques. After all, this art was the source of Aikido and the violent results of Aiki-jitsu techniques are both effective in the dojo and on street. I tend to disagree.
Certainly Aikido is composed of Aiki-jitsu techniques, but they were changed by the spiritual perspective of O Sensei into something other than Aiki-jitsu. It seems that both O Sensei and Sokaku Takeda (O Sensei's Aiki-jitsu teacher) could see that, and realized that what O Sensei practiced should be called something different than Daito-ryu Aiki-jitsu.
So perhaps we can consider our "spiritual training" just as seriously as our Aikido training. In fact, our spritual practices, on a deeper level, could be part of our Aikido training.
I'd like to add two warnings:
1. Don't think that because you are doing Aikido for "spiritual development" you can slack off on learning technique. If you're worried about spiritual training then train religiously.
2. O Sensei left Aikido to the World, not the people of Honshu or the Japanese or any special group of humans. If your flavor of spiritual development involves "The Bible" rather than "The Kojiki" or "The Koran" rather than "Nihongi" that's OK too.
If you like ketchup rather than soy sauce, it doesn't matter. What matters is that you get some nutrition from what you digest.