Does excerise help lower cholesterol?

I am a 43 year old female with total cholesterol of 230.  My doctor wants to put me on medicine, but I would like to try to lower it naturally.   I found all this information on line about how fiber can help to lower LDL levels.  I am eating foods that contain soluble and insoluble fiber, but I also need to know how much exercise I need to help lower LDL and higher HLD.   I started speed walking on the treadmill. I guess my questions are 1. How much cardio exercise do I need per week? 2. What should my heart rate be while exercising?  

[kenkeith]

Appropriate heart rate should not exceed 226-age (for women) and for some individuals an additional 10% reduction.

Regular physical activity can help you prevent — or manage — high blood pressure. Your cholesterol will benefit, too. Regular physical activity boosts high-density lipoprotein (HDL), or "good," cholesterol while decreasing triglycerides. And regular physical activity can help you prevent type 2 diabetes, osteoporosis and certain types of cancer.
Time Duration 15-60 minutes of aerobic exercise,  Frequency 3-5 times per week:
Type Activities; walking, cycling, jogging, swimming, roller blading, cross training, rowing etc

[Rosemary349]

If you haven't already, consider that almonds have recently got some press for being almost as effective as statin medication!  Almonds in your morning porridge oats would be a great start to the day, along with some cranberry juice (has been linked with increasing HDL).  Also red wine, it appears this stuff really raises HDL and is thought to be responsible for the french paradox, that is the fact that the french have low rates of coronary artery disease and yet consume a lot of saturated fat.  It is believed to be offset by the substance resveratrol in red wine.  I drink non alcoholic red wine every day, as i don't want to be drinking alcohol everyday.  Just my thoughts, hope they help!