I Aikido'd for several years. Since it doesn't depend on strrength, I thought it would be something I could do when I got old. The joke's on me. Got as far as brown belt and developed an inner ear problem, which makes it hard to pivot or roll without puking.
Too bad; bouncing around on the mats was as much fun as playing in my grandfather's hayloft. And it's fun to watch.
Aikido is more a point of view than a series of techniques. My sensei said that there are several thousand aikido techniques, but "there's really only one."
Mostly the techniques involve evasion and redirecting the bad guy, using throws and joint locks to damage him as little as possible, but the technique for dealing with the bad guy who attacks you across the corner of the bar is to block his blow and punch him off his barstool.
I keep telling myself that I should be better at verbal aikido. It seems to be harder for me to do it in writing than face to face. Words alone are not a good medium for me, and I'm afraid I sound more hostile and dogmatic than I mean to.