Jump on a bike and ride three miles to get some Del Taco, no problem.
I had to get rid of my pickup a few years ago because I was riding my bike everywhere and it had too many problems from sitting. Without a bike I’d have just driven anywhere farther than the corner gas station and would have gotten zero exercise.
The only mode of transportation that needs to be discouraged from an activity-perspective is car travel.
No, it's not, at least not in an urban environment with traffic and red lights (assuming you don't run them). Cycling is a non-load-bearing exercise. Overweight people, having excess weight, would stand to benefit much more from having to support their excess bodyweight during exercise than sitting the whole time. And being non-load bearing, cycling does nothing for bone density, and if done to excess, actively harms it: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3230645/