Moving stuff around at 10 and walking with heavy feet: not big deals, I agree with you there. But if you running on a treadmill at 6 am causes a lot of noise, that's your issue, and you'd be the jackwad for not being considerate of the other people that live around you.
Also to the OP, I echo moving to the top floor. I've been in several apartments through college, and "heavy feet" is the rule, not the exception. I'm on the top floor now, and have had exactly zero issues in the year I've been here.