When O Sensei said that the main purpose of aikido practice is not to be strong,i'm just thinking about my purpose in aikido.. Is it wrong if I practiced to become strong? Of course not strong 'outside' but strong 'inside' of me.. It's still become question inside of my head.. Thanks for answer my question..
I think your idea of being strong "inside" sounds pretty good. Why train in anything if not to become better/stronger at it? My guess is that O Sensei probably meant it's not just about being tough physically, but becoming a more potent person; realizing our fullest potential.