Re: aikido practice
When I was clinically depressed I found it very hard to be passionate about anything. Advice along the lines of "You have to be passionate or you should quit" is really unhelpful in such situations. If nothing sounds really good, you do things that seem to help a little bit, that feel a little bit good; and if aikido is one of those it's worth sticking to it. (For me aikido is a significant mood improver, but only if I train quite frequently; it doesn't do much if it's once a week.)
Not saying that this is the original poster's situation, but it's a situation some of us will be in from time to time.
My advice would be: set your own goals. If "mastery" however defined is not helpful to you right now, pitch it. Attend to how you feel and behave here and now; is aikido doing good things for you? If so, that is all the reason you need to continue. The people who fret over mastery can pursue it themselves.