I totally and wholeheartedly recommend Focus14.ch (at the risk of sounding like I work there!!). In just six months, they have done wonders with the 20 kilos of extra me left over at the end of my pregnancy and although I'm still not quite the size I should be, I feel fighting fit and on top form. They train all shapes and sizes and levels of fitness. They're based off Bahnhofstrasse between Manor and Jelmoli.