I'm starting to think perhaps it may be better to do cardio after lifting weights than the other way around. Most of the time, I don't feel strong enough to lift after I do cardio. This week was especially difficult because I live a generally very stressful life...commuting back and forth by train and bus to get around and walking for very long distances including putting in 22 hours a week at an institution where I'm taking a class. I used to do cardio before lifting because I used to be concerned that I could lose whatever muscle I may have built prior to that if I did it the other way around.