It was the same for me once I achieved my black belt in karate. It had taken 7 years to get there and about a year after achieveing this (and starting work using weapons etc) I really didn't feel the need to continue. I had achieved what I wanted and even though I could of gone on and gained another dan ranking upwards, I didn't want to.

I actually watched quite a few people not even get to black belt as they felt the level they got to was enough (or was taking too long).

Yeah, the journey was the destination. And sometimes what we think we want turns out not to be in when we get there.