I really wanted to be super preggo mum too. When I got pg this time I was running three times a week, building up the mileage, doing yoga, swimming, just started kung fu, which I loved.
When I was pg with DD five years ago, and again last year (ended in a mc) I tried to keep running and it was just hellish, too hot, too breathless, a real slog. Before DD I'd been doing full on astanga yoga for 90 mins a time, 4 days a week. I just couldn't manage any of that at all once I got pg. I got SPD and had a stupid support belt and so couldn't even do normal pregnancy exercise things like DVDs. I was going to pregnancy yoga classes and just spending the whole time on all fours moving my back around while all the other women did the legs all over the place stuff. Frustrating.
Last year I found it really really galling, and really resented all the restrictions. This time, after the mc last time, I have just decided that this is how I am, and it can wait. I can't run, I have to do gentle yoga, and I probably won't go to classes. I walk, I swim (but no damn breaststroke), I stretch, I walk, I walk. That's it, and I just have to accept it. I know lots of women manage to carry on exercising at a level way beyond my normal level, but that ain't me.
Now I'm off to bed. Cheers.