My ex owned the last car I drove. She did not have a license, so I was pretty much the only person to ever drive in the house. Now I'm out of her house, so no more car. I'm walking everywhere in an extremely car dependant area, there's public transport it just sucks ass. However, I'm liking the walking. The more I do it, the less I even think about it. My ass is gonna look great, I can still get pretty much everything I care about within walking distance, life is good.
Lung capacity goes up quick with even moderate activity from my experience, so the walking can lead pretty naturally into biking.
I see these 40+ year old dudes smoking and biking over near Chinatown here so you should be good lol