I prefer using the gym or going to a fitness class. Personally I like Combat (martial arts to music, which really gets rid of the stress of the day) and spin fit. Also walking loads, while pushing a pram
Also there are fabby wee dvd's out there 10 minute target work - I have quite a few. Have been doing situps and ab work for years feeling nothing, but 10 minutes of the tummy toner DVD and I was in agony!!!!!