Instead of the daily 5 min walk to the local "halt" for the Marlow Donkey shuttle train, I walk the 2.5Km to Maidenhead station, as part of my daily commute. It takes 20 mins.
Instead of Bakerloo line>Jubilee line to Southwark and a 5 min walk to the office, I go Bakerloo line>Waterloo for a 15 min walk. Instead of standing idle on the escalators, I walk (run) up and down them.
Instead of going to the nearest Costa café, I go to a Gail's bakery (better coffee (& cakes) anyway) which is a 5 min walk from the office, but often I take the scenic route so it's 10 mins. A welcome break from sitting at my desk.
Then I do the same on the way home, the final walk being a great wind down and relax opportunity.
This results in a typical working week walking some 60Km to 65Km, taking some 62,500 steps, climbing 125 flights of stairs and burning some 12,700 calories.
Now, about those cakes at Gail's bakery...