Are you me?
I was out in Sydney for a week in May and managed to fit in a few runs round the coast - same basic route with Darling Harbour and the bridge, but round to the opera house and, on the first day when the park was open, macquaries chair and down to hyde park.
And, same, found it all surprisingly easy at least at the start of the week. Towards the end as work and jetlag knackeredness kicked in, it was a bit of a grind. I'm guessing it was just new, different, and coming off a few days travel-enforced rest.
Back in London with a back pain from the flight and hells own jetlag, its taken me a couple of weeks to get a basic run in.