I walk (treadmill or outside) for 30-45 minutes per day and I alternate days with a circuit/aerobic class or fitness (resistance) equipment. The problem is that I seem to be retaining a tremendous amount of fluid and/or weight.
Sounds like you are doing a great job of taking care of your own health!
For the water retention, one can always try limiting salt. This means no added salt and also checking packages for the sodium content of the foods eaten. If that doesn't work, you should bring this up with your doctor. If you have any medical problems, such as heart or lung disease that are associated with fluid retention, you should bring this symptom up with your physician immediately. Fluid retention may be a sign that these problems need to be addressed.