From this Science News article Use Weights, Not Aerobics, To Ease Back Pain, Study Suggests:
Many years ago when I first started strength training I followed the conventional wisdom that stated that you had to give yourself a day off between strength training sessions to let your body recover and become stronger. I was a man in a hurry, so I strength trained Monday, Wednesday, Friday, Sunday, Tuesday, Thursday and Saturday - repeat - and I never missed for five straight months.
For many, gyms end up being collection agencies disguised as gyms. They depend on people not sticking with their resolutions.