Mina Guli, an Australian activist seeking to highlight global water shortages and encourage people to conserve, is struggling to complete 100 marathons in 100 days across the world.

Now in South Africa, 48-year-old Guli is more than half-way through the punishing project, but she's injured and a spokeswoman said Wednesday that the advocate will walk the rest of the marathons. That means about nine hours for each one, or several more hours on the roads daily.

Guli is the founder of Thirst, a non-profit group focused on teaching youth in China about sustainable consumption of water. She started her odyssey at the New York Marathon on Nov. 4 and has slogged through mud and sand, across cities, cliffs and mountains, in Europe, Asia and the Middle East.