They only ride stationary bikes in gyms because riding a bicycle outside is death-defying with car drivers not giving a sh1t about your safety. In a sense I'm blessed living in Amsterdam, where cyclists get dedicated bicycle paths and protection by the law for being a 'vulnerable road user', so car drivers take care not to collide with a bicycle because they are always considered to be at fault, even if they had the right of way or green light.
I haven't yet been to Amsterdam, but I've watched a lot of videos on its city planning, especially for pedestrians and bikes. Really smart what they've done there. I like how all sidewalks, including crosswalks, are raised so that cars must slow down. What's interesting is the city had the same traffic congestion problem as other places back in the 70s and 80s, but they've made a concerted effort to integrate cars, cyclists, and pedestrians in a sensible way.
It's amazing how many Americans don't walk at all. They drive from their homes to their office and back with 0 physical activity.
My life changed when I started to bike/walk places. It improved almost every aspect of my health.
This is in large part the fault of city planners. After the WW2 they zoned developments as either residential or commercial, with a lot of residential consisting of detached single family homes. Result: Vast commercial zones reachable only by huge busy multilane boulevards, stores surrounded by giant parking lots (which generate next to zero tax revenue). Residential areas without a walkable corner store or tavern. These suburbs eventually become economically unsustainable and gov't's answer is to expand more.
Nothing against suburbs in general, just that they should be better integrated and maybe a bit denser.
Anyway this contributes in a major way to the obesity problem - walking to do simple errands is not a sensible or safe option.