I switched to cycling for transportation. Benefits:
1. way more access to the city
2. eliminated need to go to gym; transport time doubles as cardio time
3. freed up time to see people; 15 minutes door to door is hard to beat
I really hope US cities head in this direction. It is a no brainer for cities:
1. higher density -> lower taxes per person, higher tax rev per sqm
2. lower cost of living -> lower inflation
3. quieter; cars on streets are noisy
4. people see each other more; better social cohesion
5. kids are free from the house to do things
I biked for transportation (and fun) for years and it was great. In 2022 I moved and had no bike for eight months and hurt my back ~four times in that period.
I got a new bike about a year ago and have had no back pain since (until randomly yesterday, but I'm 41, I guess it's expected that it'll happen occasionally).
Biking doesn't seem like a back exercise, but you are using your core and flexing it a lot, and for longer than you would on any standard core exercise.
Building exercise into your day to day life is incredible valuable. If you're lucky enough to be in a place where biking is viable, I highly recommend giving it a try. It's not for everyone, but given the right situation, I suspect the majority of people would find it a positive change to start biking more. (I suspect this is true for a lot of exercise, but biking has the benefit of being a productive workout—similar to chopping wood vs. lifting weights, except few of us need much wood chopped.)
There is also a somewhat amusing argument that cycling does not waste your time. you get every hour cycled back as hour added to your expected lifetime:
Cycling is great! But it doesn't eliminate the need to go to the gym. People who rely on cycling as their only form of exercise tend to suffer from low bone density and unbalanced muscle development. Everyone should do resistance training as well.
I really hope US cities head in this direction. It is a no brainer for cities: 1. higher density -> lower taxes per person, higher tax rev per sqm 2. lower cost of living -> lower inflation 3. quieter; cars on streets are noisy 4. people see each other more; better social cohesion 5. kids are free from the house to do things