I wanted to ask a quick question about weights. I try to go to the gym everyday, and when I'm there do about 40-50mins of cardio - usually a mixture of bike, treadmill and cross-trainer. When I'm in a rush I just do the bike and treadmill, 20mins of each. Thing is, I'm almost always in a rush, and my life is about to get busier - I'm a student nurse and have a hospital placement coming up.
My question is, are weights absolutely necessary? I know that a greater muscle mass increases basal metabolic rate, but I know people who do nothing but cycle everywhere, or power walk for miles and, therefore, do no 'weight training', so I'm not so sure - surely consistent cycling, or walking also builds muscle?