I am sure that highly fit 20-30 year olds who train for marathons can manage.

I am not sure how that translates to everyday commute for tens of millions of people of all fitness levels and ages.

This 'if I can do it then surely everyone can do it' attitude is incredibly myopic given the scale of the issue. You represent less than 1% of the population (A total of 1% of Aussies report cycling to work once a month or more). Your views don't matter or don't apply for the other 99%.

Unfortunately, trying to make a solution bend to 100% of the population is equally myopic. Right now, car-based transportation networks have one set of tradeoffs that disadvantages one group of people. As silly as it would be, switching to a bicycle-only network would disadvantage another group of people. Rethinking of transportation mode-share is an exercise in decreasing and shifting the disadvantages and allocating different advantages, climate change being one concern.

I hope you see your point of argument regarding weather conditions: just because you aren't able to deal with the circumstances doesn't mean that everyone else needs to be forced into car/climatized shadowy areas.

The article is about giving space to -all- participants. Currently we highly prioritize cars due to arguments like the weather. As pointed out, weather is not an issue for many folks out there.