Last night I did 800 yards in the pool!! HOLY. Friend Dave used to be a competitive swimmer, so we did drills. 200 warm up, 6 x 25 kicks, 12x 25 arms, etc etc. I was tired, but not too bad. There's something about the water that doesn't make me feel tired unless i'm actually doing the swimming, and then i REALLY notice.
Another positive: I've been going into the hot tub after each swim and I haven't realy felt sore at all! WOOT! I'm so glad we signed up for the Y.