I used to go to the gym for cardio, i.e. I used to do 10 minutes on the cross trainer, 10 minutes walking on a running machine at 6mph on its steepist incline and 10 minutes on the stepper and then I would start on weights. However, recently I have put on weight which I think is due to the amount of wine I have been drinking! Now I'm cutting that out and trying to eat sensibly but I want to know, is 50 minutes of swimming as good as the cardio I was doing above because I much prefer swimming? I do breaststroke and do 50 lengths of a 25 metre pool. I don't swim really fast, but I'd say I swim at a medium pace. I swim in the slow lane and am usually one of the fastest.