Amazing really, after just 3 sessions. Noticed it when I went swimming the next day: the usual weariness "barrier" after 10 lengths didn't occur until 20 lengths. Carried on for ages afterwards.
Was due to start week 2 at the weekend, but got struck down by some awful bronchitis/temperature/total shut-down thing on Friday and only now (Tuesday) have enough strength (and wits) to type this.
Maybe, just maybe I'll start week 2 today (or tomorrow), but I'm not going to force things... I realise the importance of a proper rest.