OK, lemme explain this in mega simple terms. These are the components of fitness:

stretching
balancing
cardio-vascular (aerobic)
resistance (weight) training

STRETCHING
helps prevent stiffness
helps prevent "pulled-out" injuries
does not burn fat
does not build muscle

BALANCING
keeps our body "centered"
helps prevent falls
does not burn fat
strengthens our core (abdominal, back)
does not build visible muscle

AEROBICS
keeps heart and lungs healthy
burns calories (as in: weight). Aerobic activity over 30 minutes burns calories faster; however, 5 minutes of aerobics is better than 0.
only minimally builds muscle

WEIGHT TRAINING:
burns a small amount of calories
firms areas by building muscle. Even if area is "padded", the muscle underneath will make the contours look better.
helps prevent bone breaks

All of these components help us function better in life. We're less tired, less prone to injury, and more able to do the things we want. For those of you who scoff at weight lifting: do you, or do you not, want to be able to lift your grandchildren without throwing your back out?

no-cost 1-lb. weights for arm exercises: cans of vegetables.
no-cost weights, heavier: empty juice or milk containers with handles. Fill them up with water or sand.

no-cost aerobics: walking, climbing stairs, dancing.

For all of the above, even 5 minutes a day is better than no minutes a day.

I'm off my soapbox, and back to the gym today after a 1-week hiatus due to 80-hour work week last 7 days.