Great post Dan.
I have the good fortune to work with people that know a lot about how the body works and develops. Both in a health perspective and in the light of competitive sports. If I have picked one thing up then it is that there are a world of myths out there when it comes to how we learn (especially through our body) and how we develop our brain and body - not to mention the link between the two.
I believe the old saying of '10.000 repetitions' or '10.000 hours of practice' is one of these myths. I have seen some people get on the mat for several hundred hours - probably pushing thousands, without showing much improvement in their Aikido. How they find they find the motivation is beyond me, but that's a different story. The point is that Aikido - or any other budo for that matter - should become what Dan describes. A passion.. a love that just wont die.Then it starts influence your whole life. Youre spouse and children will look at you overbearing when you sit in the car or at the dinner table suddenly getting lost in a hand movement or the way you hold your cutlery. Your friends will shake their heads in bewilderment when you choose to spend your money and holliday on a week long seminar returning tired, beat up and with aching knees. Not to mention when you spend hundreds of dollars on a particular odd piece of wood shaped like a sword in stead of replacing the beat up furniture or worn out car - not to mention buying an extra flat screen TV.
Or to put it in another way.When your art start making you happy just thinking about it.. yes you got the bug and it probably wont leave again any time soon. Most people who do a competitive sports version of a martial art will either loose momentum when they get too old to compete - or they will discover the same thing when they look for new aspects in what they do. In some Aikido dojo's we get a chance to look for it at an early stage, and for me that is the best type.
Of course time on the mat can not be omitted. You wont progress unless you do - but having the mind where the body is during that practice is essential, and having the practice in your mind at other time is a great facilitator for more progress.
And at some point you may realize that you don't progress in Aikido because you want to become better at kicking butt or because you want that next yudansha level (still haven't surpassed that completely myself) but because you enjoy what you do and because your body AND mind demands to have it's regular Aikido kick. Some may use a neurological approach and say it is because we are prone to having our established patterns of neurons enforced through repeating something we have already done many times - some may approach it in a different way and mark us as adrenalin junkies, sect members, suffering from force of habit etc etc.. It all depends on the type of social/scientific approach one chooses. Fact is.. the bug is here.. and I enjoy obeying it