I was doing a bit of wall-climbing (with just a touch of real rock-climbing) while I was in Jakarta and one thing that has become popular among climbers in recent years is known as slack-lining.
Slack-lining is basically walking and doing other tricks on a slack line. Now, I'm not entirely sure why it's called a slack line, because it's pretty bloody tight, but who am I to argue? Anyway, in addition to improving the opportunities for the guards at the embassy compound to laugh at me, it's also apparently good for strengthening one's feet, ankles, knees and those sorts of things. Being as poorly engineered as I am, they're probably good things for me to strengthen. Also, it's quite fun.
Obviously a natural... I'll be doing backflips in no time.