I was just curious. I walk pretty much six days a week back and forth to school and work for several miles and then hop on buses and trains to get around in the city. Those of you who've been working out for quite a while, do you think regular walking, (if you haven't done much cardio in a while) is good for your heart as well and can help prevent heart disease? How about if you go to the gym at least three days a week to lift weights and work out without necessarily doing cardio...is that any good for your heart either?