Years ago (I think I pretty much stopped about 9 years ago) I used to do Ashtanga. Its been really interesting going back to the practice. Here are the two main things I've noticed.
1) Despite being nearly a decade older and a lot heavier than when I learned it last time (back then I used to run every day), I am not noticeably less flexible. I was pretty unflexible then, I'm pretty unflexible now. I'm also pretty unflexible in the same way.
2) When I used to do Ashtanga before (I did it for about a year and a half, and most days), I experienced a lot of releasing of emotions, particularly old emotions from my childhood. I might be in a deep forward bend and be overwhelmed by sadness, or even sometimes cry. It was during this period that I fell in love with a woman for the first time, and came out as a lez. I think in my heart I've always felt that the openings created by the yoga practice had some kind of connection with this.
Now, the emotion that comes out when I do a (crappy!) deep forward bend, is a profound sense of wellbeing. I might be pissy about my job and about my lack of permanent home, but underneath that superficial frustration is.... happiness. Isn't that great? I cycled straight home and told the cowboy about it. I said 'I'm happy. You make me happy'.