I'm a general surgeon who got into the habit of cycling to work while still training in the big teaching hospitals. I was lucky enough to work at two, both 6 km from home. Now I work just two blocks from home in a lovely big private hospital, but when I do my public lists, I always cycle the 10 km route. It takes me 25 minutes, and I'm usually in a hurry to get from my rooms to theatre, so I have a quick rinse in the theatre changerooms. I need to change into theatre garb, anyway. On those days, I just wear dual-purpose clothes to my rooms - usually a nice tank top and lycra shorts underneath my suit, so I can just shed the skirt and jacket to ride like the wind... Recently my lovely husband bought me some proper clip in cycling shoes, and these have made the trip so easy - I feel like I am cheating. And these newer models can be worn at the shops without anyone really noticing. (Now I just need them to manufacture some that look like a dress shoe!!)
Perth is blessed with lots of good quality cycle paths, and most hospitals do have a proper lock up place for your bike (except the one I ride to!). The only on-road travel I have to make is on quiet back streets, and there aren't many hills. Some of the cycle paths I use run alongside the freeway, with enough greenery beside to keep it scenic, but enough of a view to see how much rush-hour traffic I am overtaking!
With two little kids and work as a surgeon, I just don't want to find time to get to the gym: so I sold my car and am much happier for it!