Not trying to be a downer, just concerned...
If your knees are really that bad, is it ok for you to do this? If it hurts you that much to run, maybe your body is telling you something. If it\'s a muscle pain that\'s one thing.... But if it is something that training and fitness doesn\'t help, be careful. Blowing out a knee is something that would likely bother you for the rest of your life, and being a person that enjoys athletic endeavors, it would really be a shame to cause any permanent damage to your body...