Four weeks ago I started going to the gym 2-3 times a week for approx. 1 hour sessions each time. I am hoping to lose some weight and tone up my legs and was curious to how long it will take before I start to notice a difference. Currently I am using the treadmill, exercise bike and rowing machine as well as sometimes participating in weekly classes of RPM and aerobics. If anyone could help me out it would be appreciated.