>In some circles, such walks are viewed as an axiomatically good thing. You're expected to go on them, and to do so enthusiastically. You could decline, or do so under protest, but that would be seen as deviant.

You just described my entire family.

The advantage of being surrounded by folks like this is I get to exercise (as in "keep it in shape") my built-in aversion to peer pressure daily.

Not sure why you're being downvoted. I would have hoped that the introverted savants here would have more sympathy for being forced to take part in social activities

Normalization implies that there’s something abnormal about going outside for some light exercise, fresh air, and a change of scenery. I enjoy those things but it’s not hard to abstain from other normal activities that I don’t.

It’s not the only option. You can do a wide variety of exercise without a gym or equipment.

Body weight exercises are a great form of strength training you can do anywhere with no equipment. You can replace walks with runs, sprints, or interval training. If you have an appropriate body of water near you, you can also go swimming without going to a gym or pool. Start intervals of boxing the air (if you haven’t done it before, you’ll be shocked at how long 45s is while you’re punching as quickly as you can).

With a minimal investment, you can take up jumprope. An excellent cardio exercise. Alternatively, grab a hula hoop, and learn to hula.

There are tons of exercises you can do that aren’t walking or going to a gym. It’s not a binary option.

Push-ups, sit-ups and some aerobics is another option.

I doubt the lockdown rules say "only walk or bike".