Hey, is it bad to run?

i run 3 miles 3 days a week and that has been my only exercise lol. I was thinking of trying high intensity interval training the other 2 or 3 days so I am not so sedentary. my high intensity interval training would be running and walking but I want to make sure I am not creating a workout routine that will contradict (I guess that's the right word) one another. I would be doing a weight lifting session before the high intensity interval training. would that be a bad idea?
Hey, is it bad to run?
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